At 8:16 AM local time, there's a distortion in the air. A keen observer might analogize it to a heat haze, though in truth the resemblance is more superficial than anything else. 

 It lingers for about thirteen minutes, passively observing its surroundings, and then sets off. In motion, the stealth is significantly less effective, but it still serves the role of disguising just what is doing the moving, and whatever is causing the visual distortion appears bright enough to be careful of the sightlines of passerby and make good use of cover, shadows, and blind corners as it makes its way down unfamiliar streets. Does anything interfere with this?

A few dath ilani spot some movement out of the corner of their eyes, but nothing in particular comes of it. The city's cameras get a much better view of things, of course, but there isn't anyone watching their feeds live with enough care to flag it as unusual.

The shimmer sticks around for over an hour, though a lot of that time is also spent on stationary observations from better viewpoints. It ranges a few blocks from where it first made its appearance, circles around, and then makes a return to the location it first manifested to disappear completely. By 9:37 AM, there's no sign it was ever there.

Absent any information to nudge it off its tracks, the inhabitants of Schelling Point continue to go about their day in the manner they are accustomed to. Those who welcome the warmer weather make their way outside, for lunch if their schedule doesn't otherwise permit it, while others make use of the city's large underground transportation network to avoid its rays. Surge pricing pushes the average cost of chilled drinks and treats up 2%, but the predictability of the change in consumer habits means that most of the increased demand is absorbed by increases in throughput.

At 11:23 AM local time, a large marble structure supported by columns appears in the middle of a busy downtown street. The people taking up the space find themselves suddenly elsewhere, and a battalion of armored men on horseback stream out of the structure and into the city proper. No trumpets herald their arrival; the scout didn't mention any nearby military positions, but the best way to minimize their losses is to make the most of the time until that changes, so their fastest elements are set towards making contact with their opposite numbers and running down any isolated detachments.

The local residents will get out of their way, or they will be run over.

What the superheated toilet paper?

Earlier and elsewhere:

To be a noble of the Saderan Empire is to be an heir to the greatest military legacy the world has ever seen. For seven hundred years, the Saderan dragon has issued forth from the imperial city to spread the Empire's glory, and for seven hundred years, never has there been a defeat they could not expunge. Even now five thousand miles separate its eastern border from its westernmost extent, and those nations beyond its borders deliver regular tribute to ensure that status endures. Every aristocrat's childhood is filled with the tales of those heroes that achieved such victories, and of all the imperial offices, there are few more coveted than the right to command a legion. 

It doesn't usually feel that lucky to Legate Cattaneo, but from the sound of things, today might be the day that that changes.

The biggest thing they never tell anyone about being a legate is how hard it is to actually be a conquering hero in this day and age. The other downsides are nearly impossible to miss, from the immense bribes required to get the title to what feels like every other noble in the empire jumping on even the tiniest display of weakness, but somehow he'd always managed to delude himself on this score prior to getting the job. You wouldn't think it from looking at a map, after all; even the least adept cartographers were happy to display a dozen other countries on their maps, and none of them held a candle to the might of the legions, so by all rights they ought to be ripe for the picking. It took a closer and less rose-tinted examination to see the flaws that constantly bedeviled him, and no doubt had done the same to a number of his predecessors. 

Right off the bat, you could cross a full third of them off the list with prejudice. Those countries might have had their own kings or queens, but they were the Emperor's vassals in every way that mattered. Their men wandered the court and senate with impunity, ensuring they would know your plan before you even got to mustering, and the emperor was more than happy to take their lavish gifts in exchange for discouraging any foolish adventurism from his generals. It wasn't even really possible to count on victory to wipe away the stain of disobedience, because their taxes were already flowing into the imperial coffers and even hiking up the rates wouldn't make up for the shortfalls a war would cause. It could still be done, of course, but one might as well set their eyes on a neighboring governor for their trouble, especially since given a hundred years to copy the Empire even lesser nations could figure out the basics of a proper army. That left only the far-flung barbarian kingdoms as real options, and none of them came without strings attached. Marching a Legion three thousand miles across the continent to fight a war was expensive, to say nothing of the difficulties in procuring food, and with how little loot they had to go around you'd have to be able to cover most of the finances out of pocket, all for the glory of conquering some territory nobody in Sadera had ever heard of. There were always exceptions to any rule, but his fellow legates were not in the habit of leaving good invasion targets unmolested for long, and absent a miracle the best you could hope for was to imitate Prince Zorzal and just eat the cost of a ruinously expensive conquest to come out with a win. 

Legate Cattaneo hadn't been expecting to get his hands on a miracle like that, but given the proper motivation his augurs and magi had come through for him in a big way. A divine gateway to another world, one where nobody had heard the first thing about how to deal with imperial dragon knights or a proper tortoise formation? It didn't matter if he could hold it or not, even a sufficiently successful raid on another world could garner him the kind of status none of his peers had managed in almost a century, or else the wealth to parlay into another conquest entirely. He could practically see a marriage into the imperial family on the way, to say nothing of the wealth and senatorial standing, and he'd be damned before he let it slip through his fingers.

Fortunately for his ambitions, the gods had truly smiled upon him. The first stroke of good fortune was the location - Alnus hill was only two hundred miles south of Italica, so getting everything he needed into position would be simplicity itself, but it was also far enough away from the imperial capital that he wouldn't raise questions about if he was planning a coup. The second was the sheer size of the aperture in question at its greatest extent; the image brought to mind by 'gateway to another world' was far smaller than what it proved able to manage, to the point that he wouldn't have any issues with getting the wyverns through and the cavalry could ride ten men abreast. It would let him make the most of the element of surprise, especially the first few critical minutes, and would hopefully be enough to prevent any elite detachments from slowing them down by holding a chokepoint. The third stroke of good fortune was that the local rector was a yellow like he was. It was hardly the tightest factional bond, and he had certainly never met the man other than in passing prior, but some of his friends knew their friends and some favor trading was enough to get local support in his preparations.

And so it was that, on the morning of the 14th day of the 6th month of the 687th imperial year, 17th Duncanica Legion arrayed itself for battle and waited for the return of its scouts. A potent force even in times of relative peace, its numbers had swollen with mercenaries, local auxiliaries, and temporary transfers until it numbered almost half again its usual size. Though as always the it was the heavily armored human infantry that made up the core of the army's strength, they were joined by orcish archers, heavy and light cavalry, three different detachments of wizards, ogre siege companies, and as many dragon knights as the legate could tempt away from their ordinary duties.

All together they made nearly twenty-five thousand heads, which some might call it excessive, but he disagreed. For all that the history of Falmart was littered with countries that had been conquered by less, it was also littered with the corpses of generals that had taken the favor of the gods for granted and not ensured that their victory was sufficiently certain. Their blessings could be fickle at the best of times, so while he made sure sacrifice generously in the days prior he had also made sure to supplement that with careful preparation, from endless drills to the coveted illusionist wizards making their report to him right now. There was always something up to chance, but if Legate Cattaneo had his way this battle would be entirely one sided.

Again, what the superheated toilet paper?

There's a cavalry battalion charging out of a weird archway that suddenly appeared in downtown Schelling Point. And if you don't get out of the way, you're going to get run over.

...So, a team of aggressive horse-racers wearing primitive protective gear and some kind of... sports equipment just appeared out of thin air and charged into a busy street? That feels incorrect but we have so many overlapping confusions here it's not trivial to disentangle them, even to the point of figuring out how to test the moving parts of that hypothesis. They're very big and moving very recklessly, though, so we're definitely getting out of the way; our insurance injury premiums would go up a little even if theirs pays out for them being obviously at fault, and also it seems like it would hurt. It should be fine, obviously they don't want to hit anyone either.

Of course not. They're an elite military detachment, here to take down as many defenders as possible before the city has time to rally a proper defense; they don't have time to waste on random passerby. They're just not going to go out of their way to avoid it either, especially not if it means slowing down.

The streets aren't so crowded there isn't any room to move out of the way, and further off people making room for the people displaced by other people moving out of the way is just another coordination problem, but a few people still aren't light enough on their feet and get hit by a glancing blow from most of a ton of metal and muscle moving by at speed. Some of those screams definitely imply broken bones.

When you're experiencing events wildly out of agreement with consensus reality, the general suggestion is to loudly announce tsi-imbi and avoid any actions that, if you are hallucinating, might result in you hurting real people. Portals don't actually open up in the middle of busy streets, but people do sometimes experience psychotic breaks that render them unable to distinguish what's really going on. Along the street, usage starts picking up; it's not most people by any means yet, but even the ones who wouldn't go that far are very confused.

(People are still going to go help the people who got injured, though, obviously, and call emergency services.)

They don't speak the language, and any attention they have to spare from their task is going towards just how godsdamned weird this city is; humans acting slightly weird doesn't rate in comparison. If it's important, the infantry will have to deal with it.

Said infantry are, naturally, the next group through the gateway. Given the emphasis on haste, one would be forgiven for expecting the dragon knights to be next, but such assumptions rest on a fundamental misunderstanding of imperial tactics and ignorance the material reality that underlies them - that wyverns are expensive.

From the small clutch sizes that make it difficult to expand their population to the immense number of calories required to sustain their active metabolism and flight, behind every dragon knight in the legions is a lies a fortune invested over decades prior by some imperial noble house allied with the legate. Compared to such princely sums even maintaining a warhorse begins to seem positively affordable, which is Saderan doctrine has always been to take the utmost care with their use; cautious, measured deployments to favorably balance risk and reward, followed by overwhelming force to break the enemy morale and chase down the scattering survivors. If instead the wyverns went first and were ambushed when going through the gate - grounded, in small numbers, in a city held by the enemy - he could in one stroke cripple his most capable forces and anger his most important allies.

And so on the heels of the cavalry legionaires begin to stream into Schelling Point at a steady jog. What resistance do they encounter?

It would be an exaggeration to describe any part of today as predictable, but whatever the cause of the sudden street building, it's pretty clear that staying nearby is going to be at least moderately hazardous to your health. Most of the populace has backed off, leaving only a small curious contingent to examine the structure. Even at a closer glance, it still looks like stone, and it's not entirely clear how it was hidden and/or faked. If it's a prank, it's a fairly high effort one of the sort people more often tend to imagine doing than usually pull off.

(A prank is the leading umbrella hypothesis here, with shares on 'yes' already trading at about 70%; while the hows and whats are still up in the air, it's a rare ilani who doesn't understand the appeal of pulling off something seemingly impossible to make someone else's day that much more surreal).

I guess that technically counts as resistance.

The civilians can get some nonlethal spear prodding to move them away from the gate; they seem mostly fit enough it'd be a waste to kill them, but the centurion will have their hides if they're dumb enough to start looting and taking captives before the position is secure. Orders say they need a good bit more space before they start setting up the barricades or there won't be enough room for the wyverns to take off, so the gawkers are going to have to move a block or two.

Superheated - Ow! The jabs don't seem to be aiming for vitals, but nonlethal doesn't mean not painful, and even the ones that aren't drawing blood are going to bruise.

"What's the big idea here?" 

Even for a prank of this magnitude, that's going way too far; he's going to sue their pants off for this nonsense.

The barbarians are presumably saying something, but it's just so much noise to imperial ears; even the ones that know some of the regional creoles aren't parsing anything meaningful, and wouldn't be inclined to care if they did.

Ow, ow, ow. A number of people nearby do have some level of combat certifications, but when dath ilani drill those skills it's typically self-defense-only or group-safe-subdual courses and neither are predicated around fighting an organized group with weapons while unarmed; the usual advice there is "don't." There are more calls going through to emergency services now, because even without new pertinent details each reporter can still move their internal prediction market about whether this is actually happening, and more bystanders are going to join in on recording. That doesn't seem to be provoking a reaction from whatever this group is, at least, and if you predictably refrain from recording events because other people seem to have it covered then it'll turn out tomorrow that the only people with recording were working with whatever group pulled off the stunt and none of the footage shows anything they didn't want it to.

Elsewhere in Schelling Point:

In another circumstance, Mylonas would perhaps be willing to admit there was a certain humor in the situation. There were no shortage of ways a city's defenders could make the lives of cavalry hell, and some part of him had been dreading an encounter with foreign magics or battlements of archers or tight ranks of heavy infantry ever since he first learned of his role in the Legate's plan, but never had he expected that the largest roadblock in his efforts would be the vagaries of foreign architecture of all things. If you'd mentioned it to him yesterday, it would never have come to mind as an issue! After the third false start, however, he was forced to face facts - he had absolutely no idea where to even find the local administration. To his untrained eye every building in the city was practically the same, and his efforts to search those that stood out from the pack had thus far turned up a library, an indoor market, and what was presumably some sort of barbarian ritual space he didn't remotely have the context to recognize.

The locals weren't any help  - he and his men could scare them, no problem, but not one among them would admit to knowing a civilized language no matter the pressure. He'd have thought "take me to your leader" wouldn't be hard to grasp from a group of invading soldiers, but they weren't terribly smart either, and even killing a few of them didn't get the rest to wise up. Perhaps a scholar or soothsayer could get something out of the resulting babbling, particularly given the common threads therein, but 'see imbeye' was so much gobbledygook to his ears and the more comprehensible screaming didn't exactly give him new information. The only real positive of the affair was the lack of resistance - if the city did have a standing garrison, it was either well away from the downtown area or asleep at the reins, and both cases meant they could rest relatively easy when it came to retaliation. There would be time to join in on looting the place, at least once they'd done enough searching that they could defend their failure to capture the local magnates.

Schelling Point emergency services is aware of the problem. It would be an exaggeration to say they understand the situation, but they have a lot more to go on than most of the people on the ground; there are quite literally hundreds of people around the city relaying their observations to the authorities, and they've supplemented this with an emergency protocals that give them access to (almost) all the cameras in the city. Within two minutes of the mysterious building first appearing, the situation was emergency services' top priority; within five, they had already escalated it to exception handling and started roping in keepers. 

The fundemental problem about dealing with it is that it's impossible. Forget the thing it's presenting as being, which is ludicrous on its face; how you'd go about convincingly faking the evidence they're getting is still unclear even having seen it done. They've already done the tests to rule out the worlds where it's an disciplined conspiracy of supercriminals with one good trick; you've got to posit an enormous group of supercriminals of unprecedented organization that also have multiple undiscovered tricks, and even once you posit that being true it doesn't really make them any less confused about what's going on. They're not all keepers, but even the average dath ilani is good enough at cognitive self-reflection to notice the problems there. And while it's typically considered best practices with confusing situations to make small, careful changes to iterate your model until it starts cohering, the 20th percentile guess is that true lives are at stake and the upper plausible limit on the number is alarmingly high.

So you're paralyzed with indecision?

No, of course not. Even children are capable of figuring out that not deciding on a course of action is usually one of the worst possible ones in a crisis, and emergency services is exceedingly well drilled at avoiding that particular pitfall. What they're explaining is why governance is not currently scrambling an airstrike.

By the standards of its technological contemporaries, dath ilan's military is one of the least impressive parts of their civilization. They possess few grand fortresses, can speak of no great glories won in battle, and do not march in grand ranks. Across the entire world, and even including those civilian positions necessary for keeping the machine flowing within their numbers, less than a tenth of a percent of dath ilani are employed by the military at any given time, and even those slated for combat roles have often rather anemic ordinances.

Much of the reason for that is from a lack of need, but that's not the entire story. Certainly dath ilani have all been under one government for longer than recorded history*, so its deployments and procurement need only consider responding to infrequent internal threats, but even those strictly limited and knowable threats could justify a larger force. It's not even a question of money, either; certainly civilization would prefer not to spend resources inefficiently, but the rates at which they will trade their enormous wealth for preserving lives - even stochiastically, for most would not consider it a critical distinction - would stagger belief. Instead the reasoning is rather more structural, in that dath ilan does not in fact want its government to have a monopoly on force. Certainly all else equal they would prefer the armed forces capable of dealing with emergencies, but not at the cost of enabling it to stay in power without the support of the population at large, and the role a hostile military could play there is obvious even to people who phone in their efforts when it comes time to practice overthrowing the government. And since a key part of keeping those counterfactuals strictly counterfactual is ensuring nobody is incentivized to try it, there are an enormous number of checks on the army to limit what it can do, and especially what it can do in a hurry on governmental orders based on fantastical information.

One of the key consequences of this is that it's not exactly trivial to bomb one of their own cities** even if they wanted to. They could manage it once, if everyone involved in the decision making were to have themselves imprisoned pending trial to accomplish it, but - even if everything were exactly as it bafflingly seems, the difference between handling this alien attack optimally or not is conservatively thousands of lives. (There's also some significant concern about whether it would even work out that way - spears and arrows are not a particularly terrifying armament, but an army best modeled by that capability wouldn't appear without warning from a space that absolutely could not fit them with no prior records of their existence).

*A significantly less impressive timespan than it might sound, though the planet has indeed been unified for a while.

**With one notable exception, but it's the thorough hope of everyone involved that that particular contingency will never be needed.

And so for now the missiles remain unfired, even if not all the planes that could launch them are still on the ground, and a similar forbearance goes for most of their other indiscriminate weaponry. This leaves emergency services with the unenviable problem of time. Civilization does technically have plans for dealing with an alien invasion, but the assumption has always been that by and large such an event was unlikely to occur and beyond their ability to win if it did. Between dath ilan and a civilization already capable of crossing the stars... there's only so much you can do at the other end of a power gap that large, even before you consider the fact that any opponent not confident in their ability to win such a fight could trivially avoid picking it. They're putting together new plans almost as fast as the new information flows in, but they're new plans, and the difficulty of logistics in haste is as always a problem. Everything more complicated than evacuating the city is going to take longer than anyone involved would like.

And in the mean time-

Yeah. People are going to die. 

Just be glad this isn't one of the legions that likes to take skulls as trophies.

...They had not been tracking that as one of the ways this could have been worse. Why would anyone do that?

Tribune Benatus is not, exactly, satisfied with the status of the gate fortifications. It's not that they're bad work, by any means, though he's confident he could have done significantly better if they weren't racing against time - having a ready stockpile of construction materials goes a long way. The problem is the blasted city. Whatever bizarre local concrete they use to pave the streets is the next best thing to impossible to dig through without magical tools, and for some Hardy-damned reason they put it everywhere, limiting how much he'd trust the walls against any siege equipment. He doesn't trust the local buildings they've taken over as hardpoints either, not with how difficult the bigger ones are to properly sweep and the risk of an aerial insertion. It'd be better if they could just block off the staircases, but then anyone who could get there would have free reign to start raining down arrows or pitch or whatever improvised ammunition came to mind down on his people's heads, so he just has to live with the uncomfortably large troop detachments they require.

Still, perfect is the enemy of good, and unless his men missed an invisible mage there's nothing in position to threaten the gate right now. He gives the order to let the dragon riders off their leash, and the steady stream of soldiers and materials into his base camp parts to allow the enormous beasts room.

Finally.

Wait, no, back up a second here. Are those wings?

Yes? How else would they fly, hydrogen sacks?

It's not that it's inconceivable, so much as... flying creatures exist under a handful of very tight constraints, and large animals capable of powered flight don't look like that. Dath ilan has fossil evidence of a handful of species in roughly the right ballpark of size, and they all shared key traits by necessity.

Firstly, they need to have large enough wings for their size and a sufficiently aerodynamic body to have enough lift to stay aloft. Something around fifteen to one in lift per drag, in the ideal case, but certainly not less than five. Secondly, they need to be light. Every kilogram of mass in their body is another 10 newtons their muscles need to offset whenever they want to gain height, and flapping your wings is not the most efficient way to supply thrust imaginable. And thirdly, particularly if they do a lot of taking off from ground level, they need enormously powerful wing muscles. These “wyverns” fail all three, even before you consider the fact that they're carrying a rider (!) wearing heavy metal armor (!!) into battle. And you can't just say that it's genetic engineering, either; a modern sailplane can be enormously more efficient than any bird at flight, but the way it does that is by having a very precisely engineered shape, which again does not look like a wyvern.

That's a bit of an exaggeration. They do make heavy concessions to the rider's weight; much like a horse jockey, the ideal imperial dragon rider is short and slender, and their kit is stripped down as close to the bone as possible. Their armor is made of bespoke plate, ruthlessly optimized to only cover what it must and enchanted for strength so it can be hammered thin without compromising the defense. Their saddle is simple and unornamented, sufficient to allow them to stand in their stirrups and prevent the wyvern's scales from chafing against their clothes, and little more. And the weaponry - oh, there the compromises run tight and dear, much to the dismay of every enterprising legate with the idea of dropping rocks or tar or flaming oil on their foes. This also gives insufficient credit to the muscles the wyverns do have, and the powerful metabolism that fuels them - a wyvern can easily eat an unsuspecting noble family out of house and home.

And?

And they're the chosen of the sun god Flare, though he rarely bestows his direct favor on any save for true dragons. If you think these are bad, you're in for a rude awakening later.

...Noted.

By now the surroundings of the gate are clear enough that no actual dath ilani eyes see the arrival of the dragons, but while a number of cameras were smashed this was mostly incidental. It's not immediately certain to the watchers that this is an air force, both because they know enough aerophysics to doubt the wyvern's capabilities and because dath ilan wholly lacks the concept of dragons as a specific alternatephysics animal, but they can see the wings and pull back the two stealth observation drones they've managed to scramble accordingly. The numbers are quite concerning; none of their pilots like the idea of engaging a foe of unknown capabilities, and they'd be doing it at a numerical disadvantage until reinforcements finish re-basing and refueling at local airfields. Additional anti-aircraft weaponry is distributed to the mustering infantry, and the evacuation advisory increases its urgency and starts prioritizing getting people too close to leave the city in time into shelter.

It's a little late on that score. Wyverns are, when they feel the need to be, extremely fast. Not by the standards of a fighter jet, certainly, but dogfighting a vtol aircraft isn't impossible as long as it doesn't turn into a race. Once they get oriented they can cross even a city the size of Schelling Point in a matter of minutes, and unlike the cavalry their aerial view is a huge advantage in identifying clusters of people, and in particular which if any are plausible candidates for military organization.

Like, say, emergency services detachments helping coordinate the evacuation.

It was always likely that they would prove unable to actually avoid a conflict entirely here, not when the aliens have been acting uniformly hostile to everyone they meet and proven extremely difficult to communicate with. They would still really like to avoid it, but not so much that they're willing to sacrifice this many people to delay it by a bit. 

The soldiers deployed around their approach open fire.

The dragons swerve.

It's not that they recognize the guns - Falmart may technically have explosives, but only in the sense that there are some individual people on the continent who dabble in the right kind of magic or alchemy to produce a primitive version of the effect. But their riders do recognize soldiers waiting in ambush, and for all that dath ilani uniforms and armor are strange to their eyes their positioning is unmistakable.

That's not going to work like you hope it will. 

One of the biggest factors in ensuring handheld firearms took longer to get adopted than artillery is that early firearms are terrible. They're expensive to supply, their rate of fire is slow, their accuracy is abysmal, and they have a bad tendency to stop working if they get wet. Compared to a mature technology like the longbow that can cripple a man at several hundred yards if it gets past his armor, it leaves much to be desired. Even in pre-screening dath ilan it took some time for people to change over, though they largely had the foresight to prepare for it ahead of time.

These are not early firearms. They fire heavy steel bullets at over twice the speed of sound, several hundred times a minute at full bore, and if their aim is imperfect it's a sight better than any bow or sling on that score. Hitting the riders is going to be a hard ask, at the speeds they're going and with an entire wyvern between them and the guns, but if they take down their ride that's basically as good and those wide wing membranes are an easy target.

That's fine, those riders were the ones they were trying to keep safe from the attack in the first place - the wyverns are immune to small arms fire.

I don't suppose you can operationalize that?

Dath ilani soldiers will observe the bullets connecting with their targets and skittering off, though someone especially keen eyed might see one of them leave a mark occasionally.

Wyvern scales are harder than steel, thick enough that the bullets won't penetrate, and tightly packed around their body that there's no realistic way for a bullet to get through the gaps. They still transfer the kinetic energy, of course, but the scales are large enough to disperse the force, and these bullets have significantly less force behind them than an attack from a fellow wyvern. It's by no means a pleasant experience, but absent a particularly lucky hit sustained small arms fire will mostly only take down a wyvern slowly by attrition. 

On Falmart, the going strategy for fighting wyverns when you don't have your own wyverns (as is unfortunately common in the empire's civil wars) is to run away, ideally after they are deployed and before they show up on the battlefield. Where that's not an option, they've learned to cope with aiming for the riders.

It's not that they're an easy target - they're armored against that, sometimes even with wyvern scales of their own, and riding on the back of an incredibly swift aerial mount! But their armor has gaps, and underneath it is a distressingly mortal body. Missile fire typically rates second under accidental death on the job, but it'd be a different story if everyone had weapons like these barbarians. Their advantages and quick reaction let them avoid the worst of it, but a number of them are sporting bruises and broken bones and a few of them are now casualties.

Wyvern riders don't like the idea of taking casualties. You could say something about their class interests in not being killed by enemies, but it's as much a matter of pride as self preservation, and whenever a nation's archers pull off a particularly successful defense they rarely live to regret it. They're going to come back in for another approach, but smarter this time.

The soldiers aren't less ready the second time, and for all they're apparently under-gunned for this scenario they aren't idiots. Their aim is better than it was, or at least more directed at the right targets, and they're more ready for the bizarre creatures' speed and flight patterns. And they still can't let them get to the evacuating civilians.

They're not happy about that, and several more of them outright die on the approach despite their own precautions. But then they're close enough to return a little fire of their own, and they intend to replay the favor with gusto. Where dath ilani troops stand alone, teeth and claws and spears tear them to pieces; where they are clustered... their heads rear back as though to spit, and their jaws unhinge to make room as a stream of pressurized liquid makes contact with the oxygen-rich air around. Cones of bright yellow flames wash over hastily-assembled fortifications, and find the makeshift shelters wanting.

Most of them survive it. It's a simple matter of physics; human bodies are largely water, which takes a truly enormous amount of thermal energy to heat appreciably and renders them pretty resistant to outright burning. Fires usually kill people by making them unable to breathe, largely by toxic chemicals released in the burning process, and for all that it's rather impressively hot the breath just doesn't last long enough for it to be an exception to that rule.

That doesn't mean they're in any position to fight, though, not with the horrific burns and choking lungs and vision issues. Civilization might be able to make protective equipment for this sort of danger, but that doesn't mean their soldiers wear it into battle.

The dragon corps will finish them off. These may be barbarians, but they were courageous and fought well; they don't deserve to face the lady below denied even their dignity.

This is probably not them intentionally going out of their way to inflict true death as a threat but that doesn't mean Governance is not very unhappy about it. And for all that biological flamethrower CAS is a deeply bizarre way for another civilization's military technology to develop, it's clearly effective enough that refraining from further escalation is also going to get a lot of dath ilani killed. They're still nervous about the unknown unknowns, like this being somehow a horrific misunderstanding or the possibility of the aliens escalating back again and the resulting fight destroying the city, but they're out of good options and the prediction markets think this way is probably better in expectation.

The order is finally given to scramble the fighter jets, and Schelling Point's inbound logistics grid is diverted towards supplying people already on the ground with heavier equipment. 

For ten minutes, the Saderan Dragon Corps has uncontested control of the city's airspace. They don't know that they're on a specific timer, but even if there weren't more of those ?archers? deployed elsewhere in the city that they'd really like to keep from linking up it probably won't take the locals very long to think of hiding in the buildings. And they're very fast, even if they end up losing a bunch of time at every engagement actually finishing off their enemies. Compared to the earlier cavalry scouts or the masses of infantry slowly spiraling away from the gate, it's a difference of night and day.

It's a bloody harvest. Their guns are good enough to make the dragon corps pay for it, but not good enough to win or drive them off once the invaders know what they’re dealing with. They can’t just hide and wait out the riders either, because where they don’t find soldiers they go after civilians and they aren’t very careful with the heads.

It would be nice to have some kind of agreement not to go for true-killing or noncombatants, and indeed as a matter of principle Civilization is predictably willing to compensate any enemy who gives up strategic advantage thereby, but they were either insufficiently legible about this or their offer wasn’t predictably generous enough to offset whatever strategic advantage the aliens are getting from it. That’s going to go in the failure analysis somewhere, but it’s not really a surprising outcome that that particular area failed; given how mutually destructive wars are, anyone you can negotiate rules of engagement like that with is probably someone you can just negotiate to not fight with in the first place.

Falmart may not have guns, but the idea of the weapon is not beyond their ability to understand. If you told a Saderan general about the existence of a form of missile weapon significantly more capable than slings or arrows, it wouldn't be too much of a leap to realizea thing or two about the effects on warfare, and if they underestimate the extent to which a gun could change warfare they would at least be largely correct about the direction. Having their first introduction to the topic being seeing it in action is rather more of a shock, but it's not a fundemental challenge to their worldview and having seen the results it's not actually that difficult to determine roughly what is going on.

The same cannot be said of other weapon systems. One moment the surroundings are clear, and the next half a dozen wyvern riders are dead and their mounts grievously injured.

How-? Where?

Their fellows scatter, weaving around and looking for whoever or whatever just did that, but they can't see anything-

Low against the horizon, light grey paint jobs blend in near seamlessly with the sky behind. The targets are too unusual and too close to a population center for them to be confident engaging from beyond visual range, but forty kilometers is a long way spot something from when you don't even know what you're looking for.

...According to people relaying information from the close in camera feeds, air-to-air missiles aren't reliably dropping the (presumably absurdly bioengineered?) creatures without a direct hit. They're killing the riders, but that's still very concerning.

Nevermind who or how, if they have more of whatever that is they're clearly sitting ducks for it. Even if the worst is true and they're facing an apostle, though, almost nobody is actually faster than a wyvern that's moving in a hurry and they can use the buildings to break any plausible line of sight. The commander blasts the trumpet signal that was agreed upon for "break off in wings and scatter" before putting his plan into action himself, sticking close to the walls as he sets his mount to ducking and weaving down unfamiliar streets to gain distance.

That does unfortunately work to make them much harder to hit, and especially hard to hit without causing enormous amounts of collateral damage, but as long as they're spending their time taking evasive action they aren't true-killing people so it's still an operational success.  Civilization is not actually certain that time favors them in this conflict, but it seems likely enough that the next set of missiles en route can veer off and disarm themselves rather than risk topping buildings in downtown, not-yet-fully-evacuated Schelling Point.

Meanwhile, the inexorable march of time has by now been sufficient to allow other Saderan detachments to make contact with local soldiers and irregulars, starting with the cavalry detachments and the faster moving skirmisher infantry units. In no few cases this comes as a surprise to the Sadarans, who still have a fairly hard time parsing what dath ilani dress and gear is meant to signal, but across the board the results are rather mixed.

Where this is Imperial soldiers up against local law enforcement, this goes quite well. The Saderan army may be at the other end of a five century technology gap, but they're trained soldiers with the best and latest in military equipment and their opponents are not. Dath ilani law enforcement, at least when it takes the form of people physically out in the streets rather than the various detectives and analysts who actually solve crimes, are typically trained for a mixture of high-stress psychiatry and non-lethally subduing (usually individual) criminals as part of a group. Where they carry weapons, those weapons are specifically designed to not kill people even when something goes deeply wrong; insofar as one might class them as a military formation it's only relative to the entirely unarmed civilians around them. 

It's not a fair fight, and it's deeply unfair in the Sadaran's favor even before one considers the possibility of them having a numerical advantage. Armor aimed to stand up to halberds and warhammers has no problem turning aside batons, and sharp steel spears have little issue biting into flesh guarded only by clothing or blunt impact padding.

(Not being idiots, dath ilani law enforcement have been evacuating  after it became clear that they really were just going to up and murder people, but sometimes the alternative is more people being killed)

Where this is a clash between actual armed forces, on the other hand...

Fire kills.

There's not really anything else to say there - the list of military assets in Schelling Point may be anemically small and distracted by their deadly struggle with the immensely more mobile wyvern corps, but you don't need armor piercing bullets or anti-air weapons to kill a legionary. Their armor and shields help, as do their numbers and discipline, but guns are just flatly far better at killing people than the Saderan army is at not dying. That would change in a hurry if they tried to split up to cover everything, though, so their deployment listings are a desperate triage of their best guess intervention options. The trains and planes carrying reinforcements can't arrive fast enough.

Where they encounter this resistance, the imperial army falls back. Not always quickly or promptly, since this is admittedly less a principled strategy on the the part of their leadership than a belated acknowledgment of reality, but while it's possible to get soldiers to charge hard points over the bodies of their comrades you have to spend a bit working them up to it.  Instead the surviving leadership do their best to keep their units from disintegrating while they draw upon the extensive imperial urban warfare experience (forged, in large part, by fighting themselves in the empire's various civil wars) to link up with nearby units while riders fetch reinforcements. 

Mages are of course ideal for this sort of work, but the legions never have half as many of those as they'd like and losing too many of them tends to make their replacements sign up with your rivals instead, so instead that means waiting on artillery and other siege equipment. It's fortunate for their wait times that purposeful delays aren't really a concern - If the locals are going through this much trouble to keep them out, it's almost certainly somewhere that they really want to get in, and while that doesn't guarantee loot the odds are good enough that nobody's going to be dragging their feet too much. 

And in turn, absent the numbers to actually take on the main force of the alien invasion, dath ilani soldiers will withdraw in the face of any forces sufficient to dislodge them. They're here to protect people, not the city itself, and in general killing enemy soldiers is not actually a very valuable terminal goal here. They'd rather kill people than let them kill others but it would be really much better if neither was happening right now, so delay is the name of the game here.

Command would also rather prefer as few guns and bullets fall into unfriendly hands as possible, and an unsuccessful defense would be pretty bad for that goal. It seems unlikely that whatever set of constraints or alternatephysics resulted in their counterparts having an air force and wormholes but still relying on jabbing people with metal sticks to kill them is particularly stable, and many ways for it to destabilize would be very bad. The issue is probably not just needing a proof of concept but it would be really bad to be wrong about that, especially since enough kinetic energy to keep a wyvern in the sky in defiance of aerodynamics is enough kinetic energy to propel rocks very fast indeed.

Huh, victory! Nothing here looks especially valuable, but they can pry up everything plausible not nailed down anyway to be sure. They'll have to make sure to spin it as "the enemy fled before us"  instead of "we took too long and they escaped," but that shouldn't be too hard to make happen.

It's about three quarters of an hour into his invasion, and legate Cattaneo is feeling cautiously optimistic about the way things are going. It's certainly not an unmixed set of positives, especially not considering the alarming reports starting to filter in second hand about the dragon corps running into trouble, but it could be going much worse. The decision to be particularly cautious with the early scouts he sent through is seeming particularly prescient now given how total the surprise of their attack seems to be as a result, and he's also quite pleased with the amount of loot that looks to be on the table. Much of the city's contents are strange and foreign to his eyes, but coming from another world is sufficiently exotic to sell even worthless trinkets, and some of the more impressive works have risen even to his attention. The glasswork in particular has his people marveling, and he can see why - the great sheets they put in windows would bring pride to any imperial artisan, and the glass ornaments that festoon much of the local clothing are of a particularly fine quality. With any luck it won't be long before they find some of the locals responsible for doing said glasswork, and returning with such artisans would be a true feather in his cap for years to come. It would be better if they can find whatever passes for a local treasury, but even without it there's more than enough loot at hand to keep the majority of his men content.

Of course, it's not all positive news. For all that the willingness of the locals to flee rather than fight back does wonders in reducing casualties, it also makes it difficult to do much in the way of capturing slaves, and combined with his lack of local interpreters means he's no closer to identifying the local elite or rulers. Unless that changes they'll likely be able to smuggle most of their more portable wealth out from under his nose, and it seems difficult to do anything about. And as for a more long term occupation... it might narrowly be possible to keep a sufficiently cowed population of this size under military rule, especially if he could coopt the local institutions to do it, but doing that and defending the place against whatever army marches to retake it is an obvious nonstarter that would get his forces defeated in detail, and attempting it without even being able to communicate with the locals would be madness. Add in that there's some concerning news from the dragon corps as well; he has no idea what trouble they've run into, but something that can bloody their noses is a threat he has to respect at least a little. Perhaps a day to finish establishing their position before starting the process of withdrawing his forces, rather than risk snatching defeat from the jaws of victory if thrice his number in barbarians would arrive next week. 

By this point in the attack, the combined military-emergency services crisis coordination teams have started to piece together the basics of what's going on. The how and why are still incredibly baffling to everyone involved, since even the most parsimonious explanations require a large number of things they had thought they knew about the universe to be instead laughably false, but they do have a wealth of data to work with here. Around the globe, hundreds of teams are hard at work sorting through tens of thousands of eyewitness reports and camera feeds and satellite imagery and other data streams in an attempt to make sense of the madness, and of course they have a direct line to all their own forces at all times. 

From what they can tell so far, the enemy's muster seems to be at least 10,000 strong, with 80th percentile guesses pegging them between 12,000 and 13,000 thus far deployed in dath ilan. Ludicrously small for any proper invasion, even if more continue to spew through the bizarre building, but also far too many for them to simply be dath ilani in some sort of disguise, to say nothing of the fact that such an act would require some truly excellent disguise work. While the majority of the attacking forces seem to be human or animal, it's become apparent that the flying creatures aren't the only sort of bioengineering at play here. Other than their tusks and apparent resilience the greenish-grey skinned sorts might have been able to pass for a human, with some commenters comparing the work to Sparashki, but the same cannot be said of the much larger set of humanoids deployed alongside the primitive invader artillery. The heavyset creatures average over 12 feet tall, and appear to have exchanged some of their manual dexterity for an absurd amount of brute strength and surprising durability, including the ability to manhandle absurdly heavy equipment and ammunition with ease. From all observations the flying creatures are much more impressive, but it takes a fair bit of doing to get something strong enough to compare favorably to a human in power armor. 

Taken holistically it seems obvious that someone is jobbing here, because even with no skills bar biotechnology it would be trivial to do far more damage with a plague. That's bad news for dath ilan's ability to win a serious confrontation with whatever civilization is behind this (and has gotten some very serious people to work ramping up their efforts elsewhere), but encouraging news about this confrontation if their opponents aren't seriously trying to win. One of the major orders of the day is trying to figure out if whatever self-imposed limitations their foes are operating under should be getting them to adopt reciprocal terms, but the whole situation is illegible enough it'll be hard to say with confidence if they succeed in identifying it. For now, the order of the day remains the same  - to mobilize troops and material to respond to this incursion with the minimum viable collateral damage rather than attempt to bomb the gateway into rubble. There are over fifty thousand soldiers already en route by train, and by this time tomorrow they can quintuple that without compromising their ability to respond to another such incursion in a different city.

Right, so your divinations have managed to spot the cavalry, the infantry, the wyverns, the orcs, the siege artillery, and the ogres. In pretty good detail, too; if you take into account the casualties you're aware of and he isn't, in some ways you have a significantly better grasp on the disposition of most of the Legate's forces than they do.

But what about the wizards?

...What's a wizard?

You know what? That's a good question.

I'm just going to let that next part be a surprise, then.

That's certainly not ominous!

After almost an hour of marching and looting interspersed with light fighting, Saderan forces had managed to occupy nearly 6 square kilometers of Schelling Point to varying degrees of success. Absent a clear sense of the relative importance of different areas the imperial soldiers had elected to spread out in all directions at once, but an inability to effectively project forces across the river (courtesy of a handful of drone strikes and the prioritization of this goal by local security groups) and the vagaries of local elevation had left the zone of control looking more like a vague blobby shape than a neat circle, with a number of radial spokes not properly occupied by anyone where Saderan cavalry had ridden ahead of their fellows and then not stopped to secure their gains. 

The extent to which this included large buildings in the area  was also hardly uniform; near the center of the zone around the gate, imperial detachments had been diligent about going door to door and uprooting any potentially problematic staging grounds, but as they traveled outside the immediate supervision of their superiors this diligence gave way to opportunism; any soldier left to their own devices could be relied upon to prioritize any building that offered the prospect of loot over any attempt at completionism, and if the officers would in turn prioritize locked doors for being plausibly important locations they were hardly immune to the allure of wealth themselves. Open storefronts typically took the worst of it, with anything that sold clothing or shiny baubles getting a particularly thorough ransacking, but anything with a shiny facade or large amounts of glass had to take its chances.

Small and lightweight objects, including a number of pried out decorative gemstones, found their way into pockets and packs, while anything to large for that while still of sufficient value to take made their way into the hands of porters and from there onto an efficient network of wagons to head back through the gate. In the traditional imperial manner the lion's share of the resulting wealth would be split up among the legate and his command staff, but enough would go towards celebratory alcohol, entertainment, and cash payouts to keep the soldiers happy and everyone's interests pointing in the same direction. Falmart might lack the specialized language of dath ilan for describing incentive alignment, but early imperial conquerors had made the advantages of an army that actually wanted to win obvious. 

(This increased efficiency of looting had, of course, made every resultant internal conflict far more devastating to the defeated cities, but it also gave the besieging generals a potent tool in encouraging defections and surrenders from the defenders. The soldiers expected it from their leadership, particularly after a hard siege, and the only ways for locals to limit the devastation of a loss were a quick surrender or a deal with the person directing the wagons of stolen goods; when the extraction was coordinated from up aboce, hiding your most precious possessions and hunkering down to wait it out became a far less practical as an option.)

Almost nowhere else, however, were they ever actually stopped. The designers of Schelling Point had made it under the assumption that most long distance transportation would take place via underground automobile and train tunnels, but significant effort had been involved at every step to ensure the resulting construction would be both safely and pleasantly walkable. It's not true that literally nobody would have moved in otherwise, but if you wanted people to live in a city that couldn't even accomplish that much the haircut you'd have to take to prices to balance things out would be substantial. The same spacious boulevards meant to allow residents to walk unimpeded without the significant risk of crowding also permit soldiers to travel freely without breaking ranks. Moreover, even a were a successful blockade of the streets to be enacted, it would only go so far; ensuring damage to roads didn't actually prevent traffic was considered to be a positive factor in planning, to say nothing of the possibility of simply routing through a building or subway line. Absent vastly more time and manpower, it wasn't a remotely feasible possibility.

It's kind of weird how few people there are, though. Obviously it's hardly rare for civilians to flee or hide in the face of a sack, but typically that meant a lot more tightly crowded streets thronged with people attempting to move or carts of hastily gathered valuables, all the more convenient to loot out of if you managed to catch them in time. The city's still big enough that there's more than enough slaves to take back in chains, even if you're being picky, but surely the buildings in question could fit way more than that, and the initial scouting reports certainly agreed with that assumption. Presumably an evacuation given the demeanor of most people they do encounter, but it's oddly successful for one of those if it was really organized on short notice.

...What kind of evacuations are you even used to? Obviously there aren't emergency drills for evacuations from murderous aliens with pointy sticks, but there are still evacuation rehearsals in case of any other kind of unforeseen disaster, and even absent those measures that sort of behavior is obviously foolish. You don't have to be a genius to realize that clogging up the streets in a way that prevents everyone from getting out is just strictly worse than an evacuation where only some people get out. There's still crowding on the subway platforms, but at least it doesn't significantly trade off volume with travel speed there. 

They'd noticed those underground tunnels; a sign of a sizable local dwarven community was the best guess they had, especially since it would also work decently to explain some of the advanced artisanship used in local construction. If these so-called 'subways' are also means of escape, that would at least partially explain why there were so many people crowded into them, but it doesn't explain why they were all hanging around on elevated platforms instead of actually moving down the tunnels.  Perhaps it was a matter of fear, since no amount of magical lighting would make it stop being creepy to traverse Hardy's domain in a tunnel sized for monsters, and they had simply decided to hope the soldiers wouldn't prioritize following them into there?

Well, no matter. Where it happens close enough to the gate to make transportation easy, they drag out the captured civilians to take as slaves first, but the other priority there is ensuring their enemy can't use these underground tunnels against them. Wherever feasible they seal off the entrances to these tunnels, and wherever it isn't possible they leave watchers with horns to sound the alarm in case of it happening. They're not going to march down the things themselves, though; dwarves might be rich, but trying to fight them in their mines without preparing for it leads to enormous amounts of casualties from ambushes and cave ins and there's a whole aboveground city to loot.

Emergency Services is more than a little concerned about all the captured dath ilani being lead back towards the gate. On one hand it's not that many people, objectively speaking, compared to the population of the city. On the other hand, as much as it's obviously better than them being true killed here and now, it's seeming increasingly unlikely that the aliens both have and are willing to use cryonics. Not impossible, given they've noted advancements in biotechnology from the aliens already, but the people betting on the prediction markets are very bearish on the odds and once people go through the gate it's hard to be confident that they'll manage to retrieve them. And even if you assume it's only about a third as bad as a true death here and now, which is near the upper end of their probability distributions... today is, unequivocably, the greatest disaster in the history of civilization since history was screened. More damage has been done, in one city and one day, than typically occurs in an entire decade across the entire planet.

They don't think it's worth blowing up the gate to prevent. It's unclear that it would work, unclear that it won't cause someone hanging back to take things seriously in a way that would be really bad for everyone involved, and unclear that destabilizing whatever ?wormhole? is inside wouldn't have disastrous effects on the city or planet. With no knowledge of how or why the deed was done, they would have essentially no way of preventing a repeat scenario unless whatever aliens got stuck on this side happened to know the answer. It wouldn't even have worked to prevent information leakage from dath ilan, given that the first people were taken through the gate before they had the capability at hand! But it's still a very tempting option, and if they had to pick a decision right now that they're most likely to regret in hindsight it's pretty obvious what it would be. 

And it might also be the most valuable discovery in the history of civilization. That's definitely a factor as well, and for all that it's hard to weigh that against the sheer damage at hand, they do know how to shut up and multiply. Instead they're going to play for the stakes at hand, and see what they can salvage from this situation.

Hey, sir? We found another few people.

Why are you bothering me about it? Take them back to the gate, obviously, we're not going to be left empty handed even if it turns out they're too useless to be worth much.

That's not what I mean, sir. Just - look at them, and what they were wearing and carrying.

Oh, I see.

Yes, that does change things. Nicely done, all of you. Take a squad with you to escort them there, we want to make sure nobody else snatches the credit. Try not to rough them up too much, ransom negotiations always get messier if the prisoners are too obviously injured, but definitely don't let them get away and don't let anyone take them off your hands until they get to the Legate.

Yes, sir!

The prisoners in question still can't understand a word their captors are saying, and even their added context makes it hard to parse things, but it's at least not so much of an obvious disaster they're getting the signal to abort. It wasn't exactly clear that this would work, but they've been looking at the local command structure for long enough to start making guesses about how the aliens signal importance and that gives them some options to work with. They knew before volunteering that there was a pretty good chance of this ending in true death, and while that's still alarming it's at least already something they knew they were risking when they decided to train for alien diplomacy - if anything the bigger difference from their expectations is that the aliens seem human enough that existing knowledge might apply. There's another group somewhere else on the perimeter with their second best guess who with luck they'll be able to work with, but it was more important that they have someone in position to try than nobody. They'll have to operate absent most of their usual tools unless they can get things returned to them, but there's at least a radio beacon in their clothes in case they're allowed to continue to keep those.

On priors there are probably also some keepers infiltrating as normal prisoners, but while said keepers probably know about them there's no reason to compromise infosec by having it go the other way.

The legate is also pretty pleased by this development! Less than he would be if he could get information out of them too, so he'll have some translators talk to them in the vague hope that someone with a noble's education will be able to speak something comprehensible, but it's still something.

With a closer look he might have seen more of the problems with their facade as definitely aristocrats, but he's busy running a battle here and anyway you don't expect foreign nobles to perfectly match your expectations after being captured and escorted a few miles at spearpoint. Besides, if they turn out to just be rich burghers it's no skin off his back. 

Obviously they're going to do their best to cooperate with the alien probably-linguists! It's not as good as them being able to communicate off the bat and convincing the aliens to call off the attack, and their methods of language learning are incredibly bizarre, but it's in the 80th percentile for expectations at how well this is going if their counterparty is also interested in bridging the language gap to do some diplomacy.

3 hours and 36 minutes after the first sightings of the gateway in Schelling Point (nearly 16:00 local time, though they aren't actually waiting for that to begin), enough dath ilani soldiers have entered the city for them to transition from a point defense to establishing a full cordon. As best they can tell, they outnumber their enemy counterparts two to one in combatants, and preliminary engagements have been suggestive of their equipment providing a significant advantage whenever they are not sufficiently outnumbered and a decisive one on anything close to an even playing field. The wyverns remain a more difficult target, but long distance sparring with Civilization's missiles has whittled down their numbers and steadily degraded the combat capabilities of the survivors; they're still a threat wherever they strike, but they've become increasingly unable to actually uproot any dug-in positions and the amount of anti-aircraft weaponry each company is supplied with has only been going up in the intervening time. Nor will they be without air cover of their own, with a number of autonomous close air support platforms and helicopters to support the operation.

The primary load-out for their fire support is (mostly) nonlethal weaponry, since they're at a point where they think their odds of victory in these clashes is high enough that it's worth paying some amount of efficacy to limit the number of people irretrievably true-killed, but they've got heavier munitions as well in case of another surprise like the wyverns showing up or of course the wyverns themselves. They've also got a number of vehicles out and running, for taking hard points and moving heavy objects and ferrying more any supplies awkward to transport via subway line. The first task is to set up mobile barriers on the main streets, to anchor the defensive lines.

All told it's a nearly forty kilometer perimeter, and despite the river largely handling a third of the line (there have been intermittent attempts to ford it or try the surviving bridges, but none sufficient to seriously threaten the blocking forces) that's a fairly monumental task. It's extremely fortunate that their surveillance systems are sufficient to rule out needing to sweep most of the buildings, and that the invaders seem unaware of any need to interfere with their functionality. 

Some of the cameras get smashed carelessly, and a handful more taken out to take back home, but for the most part they're ignored as not particularly valuable. They're looting so they can get rich, not destroying things at random.

Regardless of the reasons, the manpower it saves is very helpful.

At the same time, though, neither is an unprecedented issue. The early empire's lack of magical institutions gave it severe problems until the collapse of Arrun in the first century, and it did not claim the premier position in such fields until Rondel was induced to negotiate a vassalship agreement nearly three centuries later. In each case, the disadvantage proved a significant hindrance until it was solved, but superior strategy, tactics, and discipline allowed imperial legions to overcome the advantage it supplied, and in the end it was they who triumphed in the conquests. Divine issues are if anything even more predictable, as the list of imperial campaigns that have been jeopardized due to a commander displeasing or failing to maintain the favor of the gods could fill entire pages. An intervention of this magnitude is perhaps more unusual, but Legate Kleonike's ill-fated sack of Bellnagho in the third century civil wars famously resulted in a quarter of his forces dead to one of Hardy's apostles before the woman in question was persuaded to quit the field. There may not be a simple solution to this sort of problem, but that doesn't mean they are without options.

Absent an easy way to distinguish the two possibilities, the legate elects to prepare for both. On the far side of the gate, a grand sacrificial rite is hastily assembled in the honor of Flare, and the legate delegates enough of his work to subordinates to make an appearance himself. With luck, the sun god will object to the slaughter of his holy dragons regardless of if the cause is divine or mundane. He can arrange some other sacrifices as well, but attending them personally is contraindicated; showing up to them would weaken the show of devotion to Flare, and it's his aid that the legate is most hoping for today.

If on the other hand it is war wizards that are the problem, he cannot count on his own mages to triumph over them in the fight. There are archmages in Rondel that could take out wyverns given the proper preparations, but he has only a handful he'd trust with the task actually with the army and they wouldn't remotely be able to match the mobility or stamina on display here. Sending them out to match spells might save the dragon corps, but only at the cost of their own lives. Instead he elects to pursue a more cautious strategy. The lesser part of imperial wizards are sent out to do their ordinary work so as to not arouse suspicion about his complete lack of magical support, but they are deployed cautiously to those locations most in need of their assistance, and hopefully secured against any barbarian ambush. The greater part go about preparing an ambush, for their counterparts in expectation and for other barbarian elites if the wizards don't materialize.

They've also gotten some static defenses put together. It's normally neither feasible nor worthwhile to put together real fortifications in a hostile city, but the Gate gives a specific target worth defending and allows them to bring their stockpiles straight into the heart of Schelling Point with vastly reduced time and effort. It's still a bit of an awkward fortificiation, what with having to work around the unhelpfully shaped surrounding buildings and how they still haven't found a good way to get through the streets in a hurry for the foundations, but imperial legions can work quickly when there's a need and the idea of having walls between them and any barbarian apostles (the legate has not officially made any announcements on the subject, but in the Saderan army rumors tend to take on a life of their own) is a very tempting one. At the core of the construction is a wooden palisade, but due to the difficulties of anchoring it in the concrete it's backed by cartloads of earth and stone, and while they can't exactly dig a ditch in front of it they can use the surrounding buildings as platforms for archers or even just dropping heavy objects. It's less than optimally secure, thanks to the need to keep a constant flow of soldiers and wagons moving in both directions, but it won't take much warning to change that.

They can see all of that, just like how they can see all the streets where soldiers are marching and all the tunnels they barred, but it's several kilometers too far off to do the outlying looters any good. There are about 200 Saderan soldiers between their first and planned second perimeter, split between three different groups; ideal for testing their methods in practice. It's unfortunately not practical to ask for their surrenders, not when the aliens wouldn't understand the words, but with any luck most of them will survive any way. Each group is set upon by a barrage of tear gas and high pressure water from a safe distance, with guns aimed and at the ready but currently silent; this might end a little badly if they're wrong enough about the alien's biology being basically like humans but they seem similar enough to make it worth trying. 

Aaagh!

Infantry centuries would have real shields to turn aside the water blasts, but this close to the edge of Saderan control it's mostly cavalry and it's not a priority in their kit. The soldiers respond about as quickly as could be hope, running and crawling and stumbling away from the blasts and into cover, but it's hard to breathe in the choking alchemical fumes and their eyes are watering and their skin is burning and mustering the focus to make optimal decisions, much less communicate them, is difficult. Rather than act as part of a unified strategy, the soldiers scatter to pursue their own individual safety. Or at least, the ones for whom it's possible; some of them are caught out in the open without any possibility of getting away from the attack, while others on horseback are unlucky enough to fall off or have their horse collapse, and often mostly not in a shape to go much of anywhere on their own power. 

It's just not practical to subdue them with superior numbers and hand to hand. They've got nets and stun guns and rifles that they'll be careful to avoid the head with, and cryogenic technicians with mobile equipment standing by. Only three of them get away from the initial attacks, and none of them get far before they're brought down by gunfire. The engagement has about 15% immediate lethality for the aliens in question and no casualties on the part of Civilization, which they hope but don't remotely expect to be able to maintain. 

None of the other Saderan units spot this happening directly. They advance forces targeted are separated from the rest of the army by enough that they're out of eyesight from any other groups, and while guns are loud they'd not so loud as to be unmistakable - not to mention the fact that most of the Imperials aren't particularly aware of their existence. The same goes for the screams - a few of the closer groups can hear that something is going on, but they don't know what. At least this once, the operation has concluded without significantly effecting the tempo of the imperial invasion.

Excellent.

Twenty minutes later the new perimeter is setting up half a kilometer further in, and they prepare to follow it up with a second operation.

None of the Saderan detachments have a good sense for what kind of numbers they're up against, but they can hear the vehicles and see the fortifications start to go up, especially in areas where the streets ensure clear sight lines further out. They'll mostly pause on the looting to link up with other groups in the area; ideally to drive off the locals but at the very least to do better in the upcoming fight. Them showing themselves this openly means a sizable concentration of force, enough that they feel good about their chances, and while they're probably overconfident you can't get rich if you're killed by barbarians

It won't be quick enough to stop them from finishing. They would have set the new perimeter further out if they wouldn't get it done there in time to fend off any attacks, and indeed they did in areas where the Saderan sightlines were enough better to give more warning. Either the invaders make their attack in small groups and get defeated in detail, or they consolidate and the army has time to finish setting up. Either way the concentration of force at each point in the line should be more than enough to deal with whatever tries to break through it, and they have a rapid reaction force just in case that prediction is wrong. It's of course also possible that the invaders will respond to the provocation by fleeing, but what they've grasped of the psychology at work here suggests it's unlikely, and indeed the imperials mostly choose the latter option. Everything is securely in place by the time the defenses are actually tested.

(In fact, this is true by a fair margin. Civilization's operations planning largely underestimated how long it would take the invaders to link up, though they executed each individual action involved competently enough. The aliens seem to either have some unknown set of limitations or are significantly worse than average at coordination problems for some reason).

The defenses are pretty weird and foreign looking. The imperial army has no real idea what to make of all the plastics and the vehicles and the transparent materials, other than that they probably aren't glass because why would you make defenses out of glass, but that's visibly a wall with a lot of guys and some heavy equipment on the other side. Possibly it's related to whatever kind of incredibly dangerous missile fire some of the other soldiers reported running into earlier? They don't have to know the exact details to realize it might be a little less than smart to just go charging in. Instead they're going to test the waters first with some missile fire of their own from a safe distance, and see what the reaction looks like before they commit to storming a fortified position - if nothing else it should hopefully soften them up a bit, and any information could be helpful.

Arrows and slings don't do much to riot shields and body armor even without an actual wall to help keep them from even making contact. Here and there it causes some bruising, but even by Falmart's standards this is not a particularly impressive attack. They can do this all day without more than minor injuries, not that they have to or that that's actually the plan.

They've also got sufficiently good trigger discipline that it doesn't make them start firing early.

If we're being honest we were kind of expecting that.

Not the fire discipline, that's actually a little surprising, but the whole point of shields is that they're pretty good at blocking attacks and they probably wouldn't be carrying them around if they didn't work as shields. Nothing for it, then, they're going to have to actually attack. Four hundred some odd imperial infantrymen gather in formation, array their shields, and then march out of cover and up the street towards the barricade.

The water cannons and gas launchers open up. Every second, 200 gallons of water under 30 pounds of pressure shoot out the barrel towards the advancing soldiers. Choking gas fills the air. Sonic weaponry, previously held in reserve for reasons of being very obvious, opens up with loud shrieks. 

The guns and drones still hold their fire, for the moment.

They advance through the streams of water. It slams into shields, staggering people, but imperial soldiers are fit and their shields are in fact actually good at dealing with blunt force. It's hard to advance against the pressure of the water, but they can hold their ground, and while the water isn't going to run out there's not enough flow to remotely stop the entire advance. It would be an exaggeration to say they are used to it, but it is not a wholly surprising means of attack. Elementalism is one of the most common kinds of wizard specializations, and if water is less common on the battlefield than earth it's still often readily at hand.

They advance through the smoke, even as their eyes water and they start to have trouble breathing. The water helps a little with it, the droplets binding to the tear gas and lessening the impact, but it's still a significant impediment and they have no masks or eye protection to go with their shields. Whatever alchemical concoction is in use is more choking than smoke, and they possess it in such absurd quantities as to make even the great sages jealous, but as long as the army can fend off the projectiles that spew it and trust in their discipline, it can be managed. They do not need to see well to advance, and for everything else teary eyes will suffice. Their comrades to the rear will warn them if that changes.

They advance through the agonizing bursts of sound, even as it threatens their balance and starts to cause bleeding. They cannot even cover their ears to mitigate it, not without giving ground to the water or opening up themselves and their comrades to whatever other weapons are at hand. Sonic magic is not unknown in Falmart, but it has never been more than a niche occurance in warfare - the effective range is always short, which limits how it can be used, and in practice it is rarely the optimal solution. For a mage who stands alone against an army it is almost never sufficient to carry the day against soldiers who will march through the pain, while for those who fight alongside soldiers of their own they always risk doing harm to their own side more than they ever do to their foes just on proximity. Somehow the barbarians seem to have overcome the latter issue, for their own soldiers seem hardly to wince at the blasts of piercing noise.

They advance anyway. 

The smart money in the markets was that this would work. Not that this sort of effort would be sufficient to fully drive them out of entrenched positions or suffice to end things without casualties, of course, and they had expected their foes to have some sort of countermeasures in reserve in their forces with which to escalate back, but they had thought if it ever came down to this many soldiers against repurposed riot gear* it would prompt a withdrawal. It's not that it's not working or they have hitherto unseen protective gear either, though there had been some guesses that the alien genetic engineering would extend to tear gas or sonic protections; the aliens are just fighting through it.

And at this rate it's not going to be that much longer before they start getting into range to use their spears on the soldiers manning the barricade, which means its time for more drastic measures. Open fire.

*Lit: Gear for rioting

High speed bullets join the much less deadly sprays of water as the army's guns begin opening up. 

It's hard to make a positive identification through the water and smoke and watering eyes, not to mention all the auditory distractions, but some of the soldiers are able to notice that this matches the reports of the local missile barrages that so bedeviled their comrades in earlier encounters. It's not a perfect match for the descriptions other groups reported encountering, but they're also not idiots, and the right move is the thing they're already doing anyway. All across the formation, the solders have been readying their defenses even as they advance. 

Their shields cover nearly the entire cross section of their bodies, and with the tight formation there's almost no room for an attack to go between them without Palapon's own fortune. These attacks - whatever they are - will have to not only get past a sturdy iron shield boss, but also penetrate the treated leather outer shell and then nearly an entire inch of solid wood behind it. Nor is this their only defense, for beyond the shield each soldier has heavy armor of their own. This is not the cured hides or soft bronze of a poorer or more primitive nation, but steel scales, smelted in the great crucibles and furnaces of Duncan's church. Outside of a handful of elite battalions and Dwarven shock troopers, the imperial heavy infantry are the most sturdily armored force in all of Falmart, and many a time have unsuspecting armies tried to take them out with arrows or other missiles and found their efforts sorely lacking. 

There are a lot of relevant differences between bullets and arrows, but there are a few that stand out in these circumstances. A trained archer can shoot ten arrows per minute, perhaps even a dozen if they're sufficiently skilled or willing to tire themselves out. A soldier equipped with one of civilization's standard service carbines can manage forty times that number without even having to try hard. And while a heavily armored infantry unit like this would have little more to fear from archers than delays and harassment, the heavy steel slugs are moving fast enough to punch straight through the shield, penetrate the armor, and still have enough energy left over to give their target a very bad time. They're typically not instantly lethal, especially with the soldiers doing their best to aim center of mass and avoid any head shots, but there's still only a handful of seconds between when the soldiers open fire and the Saderan vanguard ceasing to exist as an coherent entity. If the aliens are going to continue advancing, it'll have to be over their corpses.

For a long, terrible moment, the line wavers. It's not just a question of the shock at seeing their comrades cut down like wheat, though that of course also leaves a strong impact, but rather that psychological threat is followed up by a group of very physical high pressure water blasts slamming into second-row shields that were wholly unprepared for the impact. Even so, though, it's not enough to bring them to a halt, because they have been drilled on this. As strong as the human instinct to flee within them is, it has to clash with the tirelessly drilled response that the only proper reaction is to press on, that the army that breaks is dead and the army that endures will triumph. That pushing through a flashy attack gets you victory when you kill the exhausted caster, and withdrawing leaves them free to do it again and again until there's no more of you left to die. 

The centurion shouts his encouragement, urging them on despite everything to follow through, though it's hard to hear him over the horrible noise.

He drops. They've got marksmen in elavated crows nests a hundred meters back, to pick off any priority targets, and the angle of their shots means that the bullet doesn't need to go through anyone to get close and personal with his lungs.

When that doesn't stop things, they follow it up by dropping the second row too.

At that, they break. Perhaps in another circumstance - in open Saderan fields, whipped into a frenzy by their officers - they might have found the strength to charge through such a wall of death to close with their foes, but caught unawares in the choking smoke the attack proves simply too much for even their discipline to withstand. The imperials break, turn, and run, not as a disciplined formation but as a mob only seeking escape, and even those whose courage hasn't failed them know better than to hope for victory now that their fellows have put to flight. They join into the pack, running and pushing for cover, and only careful civic engineering from the street's designers keeps more of them from slipping on the wet concrete.

Some of them are going to be sick. This isn't what they signed up for, isn't what they trained for, there are all those bodies cooling in the street and there's blood everywhere and they look just like any other humans, why didn't they just stop -

There's some pursuit, with nets and more gas, but there's not a good way to nonlethally stop people from fleeing en masse and they still need to make sure the area is clear for emergency responders.

The medical and cryogenics teams, on the other hand, get to work as soon as its safe. This is a lot messier than the norm, and it's awkward trying to do their jobs in gas masks and hastily-assembled body armor, but even if this is the worst any of them have ever personally seen they're at least used to the idea of seeing mangled bodies. Besides, their job here is to help people, and there's enough of them in one place that the triage doesn't need to be too ruthless just yet.

They're not going to get everyone. Bullets are lethal even when you aren't actively trying to kill people, and some of the head injuries are severe enough that it'll probably cause problems for unthawing them. But at least the response is prompt, and there's a lot they can do a minute after the injury that would be useless in five. Only about half the people lying on the ground need immediate cryogenics, though some more of them might end up getting frozen over the next day if their situation deteriorates.

The still-living soldiers attempt to prevent this!

They're outnumbered and heavily injured, and they're up against stiff opposition. Dath ilan is good at using superior numbers to restrain people without hurting them; if there's any combat skill that Civilization can be said to have mastered, it's that. Neither their struggles nor screamed invectives slow things down, though the consent for treatment is... dubious enough to be concerning. It's one thing to cryogenize people to save their future - though the resemblance to execution might be a cause of some of their other problems-, but another to offer mundane medical care that they might have opinions on if they were more able to communicate. It seems likely that they would want it, but the prediction markets don't feel confident enough to trade much above an an 80% average holistically.

This would be much easier and less sketchy if they shared a language and could actually communicate with the patients, though being believed might still be a real problem. Hopefully the linguists will be able to get on that soon.

They're not going to get a ton to work with from these prisoners, since even the ones that aren't in extreme pain are not necessarily feeling the most cooperatively inclined, but there are a lot of Saderans in Schelling Point right now and most of them speak the same language.

Why would they not all speak the same language???

Over the next half an hour, similar engagements play out across the city. In each attempt Civilization iterates on their initial playbook in the hopes of a better outcome, to mixed results. Concussion explosives prove a particularly useful tool in this arsenal, as they actually end up sufficient to regularly halt Saderan advances without needing sustained gunfire support, but they're also concerningly lethal and indiscriminate, particularly when it comes to avoiding head injuries, and Civilization does not actually have a particularly large stockpile of them on hand. Attempts at blinding lights manage disorientation and prove useful for the purposes of safe withdrawals, but fail to actually stop the soldiers, and it proves rather difficult to find an alternative to bullets that works without killing; as predicted, rubber rounds are only weakly effective against skirmishers and nearly wholly ineffective against a full shield wall. 

To make matters worse, in addition to the casualties they inflict on the invaders, dath ilan's forces steadily weaken in turn. Many people prove incapable of continuing lethal operations after their first attempt, often even when they are in a supporting role rather than themselves killing, while others remain willing but their participation is psychologically inadvisable. Joining them are a steady stream of injured soldiers, as blunt impacts, lucky arrows, and in one case casualties from a missed ambush start taking their toll on the dath ilani vanguard. Their combat effectiveness is being degraded significantly more slowly than that of their foes, particularly given their superior troop numbers, but it's still not exactly an ideal outcome by any means.

The Saderan empire is also learning from each engagement. Not nearly as quickly, since they don't have a massive unified command and control apparatus or instantaneous citywide communications to help, but they're not actually stupid and war is their core competancy. It also helps that there are a lot of Saderan survivors from each engagement, especially if you count witnesses who weren't themselves participating. The first engagement in any given sector takes them by surprise, and largely only varies from the first actual engagement due to differing material conditions and changes in Civilization's strategy; Imperial forces across the board are largely unprepared for any of the crowd control methods dath ilan employs, with cavalry detachments in particular suffering the most from these efforts. Sometimes the barricades dath ilan has been constructing is an impressive enough advantage or the dath ilani troops in the area have them sufficiently outnumbered that they think better of any attempts, but when those aren't true, nearly to a man they respond as they've been trained. They retreat back from the point of contact, link up with other detachments in the area, gather in formation, and attempt to dislodge whatever isolated hardpoint they've come upon, either with a frontal assault of a multi-pronged envelopment.

And they fail. Not always cleanly, but Civilization is set on over-determining success at each point and no amount of discipline will allow them to overcome that with spears and shields.

This doesn't last. By the second or third fight in a given city sector, dath ilan has to deal with larger quantities of imperial troops as lines collapse inwards, and these units have had time to hear from their fellows. In some cases this takes the form of hastily donned and sliced cloth wrapped around the face and whetted with water to serve as protection from the smoke, with efforts are made to cover ears to protect them from the piercing sound, as part of a preparation for a second go at things; the masks prove useful enough against tear gas, but the noise still sets their ears bleeding and there's nothing they can do about the bullets. In others, particularly where the first engagements were particularly one-sided or brutal, this means they outright give ground in the face of Civilization's advance. The details vary, at times turning into attempted ambushes or attempts to fortify hard points of their own and at times leading to withdrawals to more advantageous ground, but these groups prove rather reluctant to advance down open corridors with clear firing lanes into the same missile troops that reaped a bloody harvest of their comrades. Besides, they shouldn't be fooled by the wide open streets; this is urban warfare against an dug-in opposition, no matter how weird their magic and barricades, and that calls for a different strategic playbook.

They didn't really expect to be able to take out the entire alien invasion by piecemeal engagements against a few hundred of them at a time, but it would have been nice if it worked.

All told Civilization clashes with Saderan troops about a dozen times, plus twice that many skirmishes and aborted attempts. They're able to move their perimeter of control a kilometer inwards pretty much entirely around the board, and if the civilian evacuation of the city is slightly slowed by the new arrivals it at least seems less blindingly urgent; it shouldn't be more than a handful more hours until everyone who is going to make it out is in a quarantine zone somewhere safer.  

They're not too worried about the ambushes. The aliens still seem to have little idea about the massive camera network that spans almost all of Schelling Point, and when combined with drone photography and advanced imaging tools it comes out to a rather significant advantage; individual groups can give them trouble still, but anything large enough to threaten the advance itself wouldn't have a prayer of going unnoticed. The other issues are a bit thornier. There's not really a great way to dislodge soldiers from fortified positions, heavy explosives work, but they have undesirably high risk of brain injuries, and attempting to dislodge them manually gets people injured. Sometimes it's just practical to seal them in to wherever they made a stand and then deploy troops to bottle it up, but in others they have to choose the lesser evil, and it's to here that most of their limited stock of concussive grenades end up assigned.

If it helps, they're not much happier with it and are doing their best to avoid it coming up. Holing up in a secure building may be better than dying in the street, but it's also clearly obvious that being surrounded by enemies in their own city isn't a position with good future prospects. 

It does actually. Any chance you could just surrender then instead if it comes up, given both of us would prefer not to blow up the building with you inside of it?

Gods above and below, no. Dying in battle may suck, but it's a sight better than being a human sacrifice for barbarian gods and a lifetime of slavery doesn't have much to recommend it as a consolation prize. It might be a different story if they could count on being freed by their countrymen later, but the legate made it clear that this was a quick jaunt in and out rather than a proper conquest.

It's not human sacrifice! We're just chopping off people's heads so we can ensure they can be brought back to life in a future paradise!

We don't believe you and wouldn't find it particularly reassuring if we did. The best way to make it to paradise is of course to be held high in your god's esteem, but dying valiantly in battle is often about as good as you can hope for odds wise.

Figures. Though, wait, what was that about a "god"-

After the half-hour operation concludes, there's a bit of a break before the next engagement between Sadera and dath ilan. It is not, properly, a pause in Civilization's military operations.They cannot afford such a decision when every moment counts, so even when things are relatively static on the front lines there are enormous numbers of soldiers and near incomprehensibly vast quantities of material on the move.behind the scenes. Most obviously they head towards Schelling point, where the gate could start spilling out more troops or some heretofore unknown danger any moment, but they're also working to set up rapid reaction forces in every other major population center. Current market odds suggest that there's a 30% chance they'll end up using them, taken collectively across every city on dath ilan, but that's less than reassuring when dealing with black swans this dangerous, so they're going to make absolutely sure that any repeat of this sort of event will be something they can respond to promptly before hundreds die and thousands get dragged away to an unknown fate. Every minute of delay in their response time here was measured in lives and true lives lost, and that's puts a very strong incentive for haste on the table here. 

But there is still a break, because the actual troops that would be doing the fighting aren't ready for more. For all that the grand logistical machinery of civilization still turns with unhurried grace, the individual people that make up its vanguard need to to recover, to reassess, and catch their breath, and while new material may be long since en route it still takes time to actually arrive. Especially the armored vehicles - judging by the defenses the aliens have been setting up, demolition tools proofed against heavy impacts (of the sort used in avalanche and landslide zones) are going to play a critical role in ending this without excessive casualties.

Legate Cattaneo is in a foul mood. He's got reports streaming in from every direction of their advance, and it sure seems like the locals have his forces encircled, and not with a token force either. That there's a response from the locals by now isn't surprising, but the details are. Starting with the obvious, by now it's clear that their initial baffled estimates about the military presence in the city were indeed too good to be true. Between whatever took down - and is still taking down - his dragons, then the soldiers at the river crossing, and now an encirclement of this scale, it's obvious he's up against an actual army that stole a march on him. That's a particularly embarrassing position to be in, given that he's the one invading the city, and it's one that means he's going to have to play this smart.

His best guess is that he's up against a border garrison based out of a set of forts at the city limits. If the city had a sufficiently impressive set of external defenses, it seems entirely plausible for it to give them the confidence to disarm the city interior, certain in the knowledge that anyone who wanted to threaten the city center would have to fight their way in. The timing also fits, or well enough - given the distances to the edge of the city suggested by aerial recon, there's been enough time for soldiers to march their way in if they'd somehow gotten word of the invasion promptly enough. It would also handily explain the encirclement, since just heading inwards would naturally produce a force distribution to all sides, and doesn't require his opposite number to have risked purposefully divvying up their command into readily crushable detachments. From the reports he got, they even fight like it, attempting to fortify a defensive position and make their opponents take it from them. If so, he's probably not going to have much luck driving them off, but there shouldn't be much risk of them pushing in and attempting to crush his own defenses, since it'd be giving up their greatest advantage. All he has to do, then, is not give them what they want. He should form his own defensive lines, force them to come at him if they want to dislodge him, and then withdraw in good order once he's done - a simple enough task, thanks to the gate.

The only problem is, he doesn't trust it. It really feels like he's missing something - not in the usual sense, where there's something obvious he should have realized in advance, but in that uncomfortable zone of foresight where he can glimpse the edges of something he's pretty sure is going to bite him later.

He's going to move the schedule up. It's a shame to cut the looting short, especially when more than half of every denarii they bring back with ends up in his pocket, but it's not like raising new cohorts for his legion if he loses them will be cheap either, and if there's one thing that any general knows is that an army that's distracted by looting is little better than an undisciplined mob in a fight. It can continue safely inside the new lines, but anyone near the edge of their territory will have to cut it out. No more far-ranging cavalry missions, no more trawling for the city's leadership, just pickets and barricades at strategic positions there, there, and there, commanding the approaches on major roads and funneling any responses - and for Hardy's sake, he's going to have to garrison every tunnel entrance they've found, and leave scouts to keep an eye for any they missed. It shouldn't take a lot of troops to hold a tunnel like that, but if he doesn't bother to try they'll be able to march past any lines he throws up.

And while the couriers head off at top speed to relay their new orders, he gives the order to call up everyone on his command staff that isn't out leading the detachments. Maybe one of them will see something he missed.

There's a strong temptation to just take out the couriers on horseback to nip whatever they're planning in the bud, but it's not practical. They'd have to do the same for all the footbound messengers, which would be a pretty big ask, and then whatever sonic code they're using would still work fine for simpler communications. It's not worth tipping their hand by revealing the capability and killing people if it won't actually prevent the orders from being relayed. It might be a different story if they were already advancing, but it also might not - having eyes in the sky that your enemy doesn't know to be concerned about is a very useful addition to their normal camera surveillance network, particularly since they can just plug in most of the gaps it has.

Speaking of drones, there's one group of imperials that has taken notice of them. They might be easy to overlook if you're not used to looking up, but the wyvern corps has extensive training to fight in three dimensions, and they're paying a lot of attention to their surroundings; it may not have taken too long to figure out what the deal was with rockets, but coming under fire by absurdly deadly high speed explosive projectiles that blend in with the sky and outrun the sound of their arrival has a way of making you paranoid. Even once they got the hang of mitigating things (in particular that the rockets are essentially incapable of cornering at speed) and they started showing up more infrequently, its incredibly exhausting to stay on edge for hours on end. It's done almost than the actual losses to their numbers to whittle down their combat effectiveness, especially if you also consider all the time they spend avoiding being killed instead of destroying enemy formations.

It's enough to make them murderous, even by the standards of a group that's known for dispensing violence at the drop of the hat, and has gotten a lot of drones destroyed as collateral damage even in addition to all the ones that get destroyed completely purposefully in the hopes of blinding a person behind the familiar or getting rid of a distraction that interferes with them noticing the attacks. They're not used to being killed hunted like this and are not used to not being able to accomplish things and the intersection is significantly worse than the sum.

That's actually annoying, though they do their best to not leave any sign of it and encourage more destruction thereby. In addition to being expensive and helpful for keeping an eye on the various troop movements, the drones in the air are also very useful when it comes to actually ensuring that long range missile fire ends up where they want it to and not slamming into some completely unrelated building. It's not that they didn't know hitting fast moving aerial targets from dozens of miles away in their own urban environments would be difficult, but they hadn't ever expected to actually need to do it; there are several reasons why air defense systems will automatically shoot down any planes that get too close to a city without changing course, and it's unfortunate that the portal allowed these creatures to effortlessly bypass them.

The only small mercy is that while the beasts in question are extremely dangerous, they seem to lack the ability of more traditional aircraft to destroy large buildings with blunt force impact. This means they can settle for harassment and a steady stream of destroyed drone platforms while closer ranged (and more accurate) measures are arranged, rather than blowing them out of the sky asap and damn the billions of labor hours and thousands of lives in collateral damage.

There's a change of plans. Message from the legate - we've found the enemy army. He's expecting a big fight to come up soon and he wants you ready to participate. Stop hunting around for isolated detachments, and find somewhere secure to hunker down and catch a breather.

And stop trying to get revenge?

It's not like we've gotten anywhere in particular with it, and if we kill enough enemy soldiers we can at least make their leaders regret it. Besides, are you saying you don't want to take your frustrations out one some actual enemies?

...No, I didn't say that. 

They can, for the most part, do as he requests.

(Some of the riders pick their resting spots poorly, and get punished for it with direct rocket attacks or collapsing the building around them, but they've mostly learned better by now)

At 17:37 local time, 6 hours and 14 minutes after the gate first became visible in downtown Schelling Point, dath ilan's military is ready for another serious push. Sunset won't be for another three hours, but they'd like to get the delicate breakthrough operation finished in daylight since it's going to require a lot of precision. (They're also a bit unclear whether a night attack is to their favor in general; they have night-vision equipment and can control the city's lights, but the moon is going to be bright and low light vision is a likely target for genetic engineering, to say nothing of how visibility favors the side with longer range weapons).

They've been gradually tightening the radius until now, but enemy fortified positions have brought a close to the feasibility of that strategy, and they've made good use of the time to prepare their newly updated strategy. Unlike before, there are no simultaneous assaults all along the perimeter; it would mean stretching their heavy equipment thin, to little actual advantage relative to bypassing them. Instead most of the perimeter forces are instructed to hold the line, though where feasible they are permitted to offer probing assaults in the hopes of hiding that and (ideally) discourage any redeployment to the actual breaches.

There are two main lines of advance, each separated from the other by just under two radians of the perimeter, each targeting a random selection from a list of suspected enemy weak points. Ideally it will be unpredictable in advance which exactly they would choose until it's too late, aided by some similar buildups at other likely locations in case the enemy has better intelligence than heretofore demonstrated, but the plan doesn't count on that and should function acceptably even if foreseen.

Are you sure about that? This might have gone your way before, but this time we're the ones with defensive positions, and while these may not be proper fortresses your buildings are pretty sturdy and we've had time to reinforce them. Plus this time you're the ones trying to advance through a field of missile fire to root us out, and whatever your weird armor is made of won't be enough to make you actually immune to it. 

Not at human scales, no. But they're not limited to those. When the vanguard arrives, it takes the form of armored vehicles with heavy composite armor meant to resist rockets and high-velocity kinetic penetrators, supported by repurposed firefighting helicopters, drones, and a handful of actual military VTOL close air support. The arrows and missiles - even the heavier metal rounds flung by superhuman slingers - bounce off sloped armor to essentially no effect, and the first helicopter opens up with a deluge of water. They're not going to take this without killing people, but there ought to be less irrecoverable heads from this than a proper bombardment.

The helicopters' radar range-finding and camera feeds suddenly fail without warning, simultaneously.

That's alarming! They're entirely separate systems and heavily redundant, that's not easy to pull off even if you know what you're doing. Fortunately the helicopters do have large, reinforced windows for back up line of sight guidance.

Those are down too. It's totally dark, pitch black out there all of a sudden; the helicopters are now lit by solely by internal light sources.

Even stranger. They turn on the floodlights, and attempt to radio a report asking for assistance figuring out what's going on.

No dice on either; there's no visible difference between before and after they hit the button to turn them on, though the light system does at least claim to still be operating properly, and in fact they're not picking up radio chatter either - not from mission control, not from the other helicopters, not even from stations broadcasting from hundreds of miles away and safely distant from whatever is going on in Schelling Point.

What the superheated flash-compressed excrement?

It's not an EMP, that wouldn't explain the darkness or half the other data, and while the helicopter has some resistant shielding against that there's no way everything internal would still be working. What does their gyroscopic autopilot system say about their position? 

It seems to think that they haven't moved since they came to a halt and started hovering when their instruments went out, and were moving as expected prior.

The radio blockage and darkness feel almost like a faraday cage. Did they somehow get trapped in... a spontaneously appearing box? No, then it would be dark but the lights on the helicopter itself would still illuminate things, and also they probably would have crashed, and it would be showing up like crazy on the radar rather than just not at all. A cage of nanobots? Some kind of implausibly light-absorbent material that dath ilan has never heard of, that also absorbs radar echoes? Neither are consistent with any other displayed capabilities other than the portal, and doesn't really leave them less confused, but it's at least at least not immediately disprovable. 

They can't continue the attack run, though, even if whatever is causing this wouldn't be lethal to collide with. The inertial guidance should insure they aren't about to crash into something but it's really really really not designed for this kind of scenario. It's meant to keep you from going off course in long flights, not for precisely navigate between buildings with no sensor data or detailed 3d map because that's actually an insane thing for it to be doing, much less do aerial bombardment totally blind, which is so absurd the designers had quite literally never even considered the problem. If they just hover in (approximate) place, can the rest of Civilization figure out what's going on and solve it? They have plenty of fuel, at least.

The helicopter begins to shudder as its motor whines, and the blade sensors start reporting something interfering with their functionality and dropping their RPM. And... the icing alarm is going off? 

When civilization designs aircraft, they put a lot of effort into ensuring they are safe. Not "unlikely to crash," not "functions fine in atmospheric conditions;" as much as possible, the engineers putting them together did their best to ensure that the only things that would knock an aircraft out of the sky are bad decisions by their pilots, and then tried to make that as difficult to as possible. But while the average purchaser is willing to accept some pretty steep costs chasing diminishing returns in safety, they don't tend to have unlimited budgets either, and they don't, actually, have magic. 

A helicopter of this sort is rated to maintain 90% functionality after an hour of typical atmospheric rime from stratus clouds with water content up to 1 g/m3. It's overkill, for most inclement weather, and enough to make a safe landing for almost anything else.

It's not overkill for hostile action; being overkill for hostile action taken generally is probably outright impossible.


Civilization has plans for what to do in inclement weather, and drills pilots on what to do in icy conditions. There's further drills on what to do in sudden onset conditions, and when their visibility is shit, and even how to recover if you missed the very obvious warnings that it was building up or there was a sensor error. This isn't quite like those, both because it's far more severe and because none of them were about what to do if you started losing control in the middle of a battle over an inhabited city. Fortunately, these aren't ordinary pilots. There are a lot of reasons why someone wouldn't want to participate in this operation despite how critical it seems likely to be, so Emergency Services has offered a truly staggering upfront payment and bonus schema to align everyone's incentives as much as they can. Insofar as time and location permit they've been hard at work ensuring the crews in the air are the absolute best available, including flying them in from the other end of the continent. Despite the time pressure and unprecedented situation, most of them come to the same conclusion within a few seconds of each other. Landing the helicopter is hopeless; they don't have enough precision on where they are relative to the city to know if they can safely descend, can't reasonably expect that to change without knowing what happened, and misjudging it would get them killed from hitting a building on the way down. Staying where they are is also hopeless; at the current rate of icing, it won't be long before they crash anyway.

That leaves two options. They can try to quickly gain altitude so they can fly away without crashing into any buildings, and hope that this is both not an instantly lethal mistake and that leaving the vicinity will fix things. Or they can set the helicopter on autopilot to do that while they abandon the craft, and hope both that the craft doesn't hit anyone anyway and that they survive the landing. 

Those are terrible plans. Surely we can do better than that.

Sure. Just as long as you come up with it in the next few seconds, with no aid from anyone outside the cabin, while also attempting to figure out what's going on.

And also every second spent makes both plans and any replacement less likely to succeed.

There's going to be such an incident report later if they survive, wow. Seven of the helicopters elect to ascend.

The helicopter's residents experience the qualia of upwards acceleration, and hear rotor sounds that would suggest they are ascending, but receive no other evidence of this state of affairs. The darkness does not fade as they rise. The ice buildup... seems to slow down, maybe? But it's still alarmingly fast, and it's becoming a serious impediment to flight. Fortunately there's no real risk of them crashing; if there's one thing dath ilan is particularly good at, it's zero information coordination, and their initial positions give an obvious random seed.

Once they manage to get some distance from the battlefield, the build up of ice first rapidly declines and then stops, and the darkness clears not long afterwards; Radio comes back before visual light, but by less than a second. Of the seven, four are shaken but not seriously encumbered; their buildup was sufficiently slower*, or their reaction speed sufficiently swifter, or their initial position sufficiently more favorable, that the build up of ice is still within emergency tolerances and suffices for them to make it to a proper landing zone. Two more need to make emergency landings as soon as they can see where to touch down and will need significant maintenance to be flight-worthy again - not to mention a few injuries from the hasty touchdown - but are largely intact. The last loses power and crashes with all hands. Their heads mostly aren't in good shape, but emergency responders pull them out of the wreckage quickly enough it might not be hopeless for all of them.


*Though they cannot effectively measure it during the incident or communicate the data to each other, later investigations suggest that some of them iced up noticeably faster than others; while even the slowest is significantly faster than almost any natural conditions, the difference in rate between the slowest and fastest to freeze is at least 20% and possibly as much as twice. Physics simulations suggest this was correlated with the outcomes observed, but not entirely predictive.

Of the other four helicopters, three of them stayed because they focused on evacuation with passengers attempting to hastily don and utilize parachutes*. It would be better if they could use ropes and simply rappel down, not to mention safer, but they don't really have the time. They're not all okay, but the helmets they wear suffice to keep their skull intact through any impacts and protects their most vital organ, and if some of them die they to this or alien arrows, they at least still have a future.

The last fails to make a decision in time.

* Most dath ilani aircraft do not have any sort of parachutes, but the likelihood of a helicopter crashing in a warzone was considered plausible enough that they were worth the weight to include. They look different from the sort traditionally used in earth aviation, with a larger canopy; base jumping is not a particularly popular sport in Civilization, but not so unpopular a planet of a billion lacks the equipment entirely.

And thus has the decision made for them. It would, perhaps, have had a chance at its own evacuation, but when some of mages lose their links with the fleeing helicopters, they change targets. It goes down with all hands, ice suddenly building up even more rapidly than before.

It's not, objectively, the worst thing that happened today. The equipment is expensive, but civilization can afford to replace it, and if the true deaths are unfathomably high for normal operations they're still not the majority of those who perished in the last 12 hours. It still hits really hard.

They knew going into this that the aliens had bizarre anomalous capabilities at odds with their normal combat performance and were not in all ways best modeled as a primitive army of dath ilan's past. The ability to open portals wasn’t even an isolated example, but this was still not... what they expected to happen, and it's still a bizarre combination of incredibly devastating and incredibly restrained. The lesson is learned, though; the aliens are either bizarrely capable of downing flying machines, or else consider them enough of an escalation to escalate back, and in either case dath ilan doesn't want to lose more helicopters and crews trying. The decision to keep the fighter jets far from the city earlier is feeling very justified right now. 

The order goes out to redirect the advancing troops towards the landing zones for the parachuters, as well as encircle the crashed helicopters; it's vitally important that they advance until they can cover emergency services medical officers getting at the bodies, and hold it long enough that they can do their work before withdrawing. The assault itself is being called off, though, due to the need to reorganize and reassess. They're going to have to figure out if there's a form of air support they can and should risk, or else how to handle things with just grounded assets, and also buy time to see if they can start predicting some of these twists in advance rather than after people get killed. And they're probably, much as they dislike it, going to have to start holding back less; their earlier use of gunfire on enemy air support didn't provoke an escalation, and it's increasingly uncertain that they can win this fight without either suffering or inflicting significant casualties.

Victory! That'll teach them not to mess with the empire.

Some of the troops had been getting nervous hearing about the barbarian advances through rumor and garbled word of mouth, but as impressive as their armor is it's pretty clear they aren't actually all that, and the bosses clearly have the plan to deal with it. The mood along the defensive lines is significantly more cheerful now.

It would have been better if that had gotten all the local  ?birds? They’re not dragons or gryphons, not of any variety he’s ever heard of, but his experts were not particularly confident in any guesses as to what they were instead.

The first engagement was one sided, just like you always hope for in a clash with enemy elites, but they’d have to be spectacularly stupid to let him do it again. If he’s lucky, it’ll at least have been enough of a scare that they’re not in a hurry to try it again. If he’s not lucky, they’ll be angry enough to trust in whatever countermeasure the barbarian wizards can cook up, and his legion will get a chance to find out firsthand just how effective the barbarian air cavalry and wizards are. There’s little he can do to affect that decision, save through beseeching the gods.

But he can take steps to mitigate the results. His best wizards will rotate back from the front lines, to conserve their power and ensure they don’t fall victim to whatever has been targeting his dragons; lesser mages will have to suffice to handle any threats that emerge. And he can rearrange the lines, sending his subordinates to do the job wherever he lacks the information to decide properly. Some places took the abortive assault better than others, and depending on why will need to be either reinforced or abandoned. And he can make sure the wyverns know to expect water magic from their counterparts.

All told, it's a bit under five hours before the next major operation gets underway. Unlike the previous, it's not intended as a major push to regain territory or press to the portal, but that doesn't mean they've been slacking on the preparations. What can they observe about the disposition of the alien forces?

At night, while encamped? Well, that depends on how close they're getting.

Assume for the sake of argument that they're doing aerial recon, from mostly a couple thousand feet out but with a few closer flybys, and that said scouts have vastly better vision than any human but no ability to see through solid objects or otherwise get a good look at anything without a clear line of sight to the sky. As well as of course numerous groundbound observers at various distances from the front lines and a handful of interspersed security cameras still relevantly functioning. There are also teams of experts standing by, to hopefully get the most out of all the individual data points they can get their hands on, but that's the kind of thing that famously offers rapidly diminishing returns even when you aren't this confused.

(They don't have a satellite to supplement it, unfortunately, as reassuring as it would be as a way to supplement their potentially risky drones. There's an amount of civilizational capability that would allow them to relocate a specialized ground observation platform above an arbitrary city this quickly, but it's not one they had, and there hadn't happened to be any bizarrely convenient for the task).

Does that include sounds?

Yes, quite well actually - they've got actual audio recording on the ground, and can use laser mics to pick up more if it's being said somewhere convenient. But it's a bit hampered by the fact that they still don't have a working translation for the language, even if they think they've got some of the words from context clues.

In that case they can get a fairly good look at the location and disposition of most of the troops and sentries. The empire isn't trying to make it obvious, but they don't know what the attack surfaces they're dealing with look like, and even if they did it would be pretty expensive to fully prevent.

From the looks of things, they've got sentries along most of the ring, but they're not always densely packed - it's possible, maybe even probable, that dath ilan is missing some better hidden ones in some places, but that still leaves large areas inadequately watched if they can figure out which ones. The majority of the sentries they do have are scattered around the four big encampments near the current front lines - from the looks of things, their primary worry is a night attack on sleeping soldiers. Most of the people on guard don't look like baseline humans - the green-skinned soldiers, in large part - but there are some humans among them, and a scattering of other appearances. Comparing all the soldiers they can see to everyone they think has gone through the portal, minus battle casualties, suggests they probably are missing less than 10% of the enemy forces total, but it could easily be lower.

They'd like to get crosstabs on comparison to everyone they've seen before, to try and get an idea if any group isn't showing up where they can see, but there's a lot of detail missing for that. Most of the soldiers they can get eyes on aren't being observed in that much precision - enough to confirm there's a person there,  and in some cases which sub-variety they are, but it's easier to tell someone is there than to tell who it is - particularly so when technologies like thermal imaging enter the equation. They'll still sort and tag the appearances they can, though, in the hopes that an elite team of face recognizers can track any patterns when compared to earlier or future observations.

Elite teams of what?

Anyway, it's a reasonably well set up set of defenses. Not as good as if he could get his men back to the actually prepared buildings by the gate, but in addition to all the much-needed money he'd be giving up retreating that quickly would make him look weak, to his rivals learning about it later if not to his men, so needs must when Emroy drives.

It would indeed be quite inconvenient if they were trying to take out the enemy soldiers or slip an army past, especially nonlethally with only the capabilities they've already demonstrated. But in between the front lines and the inner fortress is a lot of empty space, practically undefended, and with a combination of night vision allowing them to move without lights, underground tunnels, and aereal overwatch they can slip through the lines and pass unimpeded to very nearly the inner citadel itself, hopefully without issue. They want eyes nearby the gate, in case any of their hastily assembled sensor arrays can actually get anything out of it that would give them a better understanding of how all the alien tricks actually work, and some special operations teams with them in case they end up needing it later. There's enough situations going forwards where additional vectors to scramble a rapid response with could be key, such as whatever took out the helicopters deciding that drones are fair game too. If all goes well, they won't get noticed.

...By which they mean, unless they're wrong about which possible blindspots happen to have observers and things also go in the bottom 10th percentile of expected outcomes, or else they're enormously wrong about something else major going on here. For some reason it felt important to specify they weren't trying to bet on a slightly weighted coinflip here, even though you'd really think that goes without saying when true lives are on the line and the conjunction of <all goes well> and <operation fails due to unexpected inputs currently trading at less than 2%> hovering around 96% would suffice to clarify if not.

He didn't actually do this, because he isn't completely insane. You could call him a bold general, inclined to risk defeat in pursuit of victory, and not be wrong, but it's not like being careful is a foreign concept. He's got the sort of caution that leads a general to wonder if this wide open valley they're walking into is an enemy ambush, and knows how to hedge against assumptions being wrong in the face of surprising enemy competence - a skill that has already served him well a few times this last day. But he doesn't feel the slightest temptation to leave his troops undefended against a threat that actually exists just for arbitrary paranoia, so his best secret observers are instead keeping watch to better raise the alarm around the places and people it would hurt the most to lose.

With that said though, the gate is his single most critical military asset right now, so in addition to the fortifications he's god several thousand troops stationed in the area and a handful of more esoteric defenses. 

In that case they'll abandon the approach of their first choice of forward base, and set up on the 14th floor of a high rise a two and a half blocks away from the gate fortress. It doesn't quite get them line of sight on the gate itself, but they can get over the walls, which is enough to get eyes on  sizable portions of the fortress interior. It's neither the best possible position for sniping nor for observation, but it's solid at both and far enough away they probably won't be noticed. 

Saderan military engineering is perhaps not optimized for cities where the buildings get this large, yes, and especially when it's not a one-off structure you can secure separately. In their defense making a fortress that can't be seen into by at least one of the surrounding skyscrapers would be a significant ask, and some quick examinations on demolition feasibility - 

Of course it's difficult to knock down a skyscraper, that would kill people! If your skyscraper was easy to knock down the insurance premiums to have it in a city* would bankrupt you inside a month.

*Doing it outside a city is much more feasible, especially since the land is also less expensive, but it's still not a common occurrence. Most people who build skyscrapers aren't in the business of getting them pointlessly knocked down, there being far easier ways to light money on fire; as a practice it is largely reserved for the sort of ultra wealthy supervillain-gendertrope who finds themselves unsatisfied with any lesser visual setpiece.

- made it clear that collapsing the larger buildings, in addition to being dangerous to anyone in the area, would be completely infeasible without a full team of siege wizards for each one.

Which, as little as they understand the alien capabilities, is not something they appear to have. It's good news for the team camping out in one now, and hopefully good news for the detachment that'll try and slip some autonomous monitoring equipment into closer structures.

It sure sounds like everything went as planned. Their next operation is in another 4 hours -

Actually, I think you'll find that it's our plan that comes up next. Eight hours after the last engagement, under the cover of darkness, the imperial dragon riders are returning to the sky for night operations.

It's a bit of a risk, and the typical rule is that you're not supposed to do that with your dragons, but there's good reason for it. For one thing, it should be significantly safer - it'll be harder to see the wyverns under the cover of darkness, and given how long it took between their arrival and the first attacks it seems unlikely that whatever countermeasures they had are something that can work tirelessly day and night at full efficiency. Secondly, this time they have targets - not a meandering search pattern over the city for important buildings or pockets of resistance, but actual troop concentrations, and with any luck whatever eyrie their counterparts flew off to after taking their own licking. They can leave cover, head in for the attack, and withdraw before there's time to organize a real response.

And, admittedly, it's not like the alternatives are amazing either. The riders resent the fact that they've had to hang around in hiding after taking a licking earlier, especially after enough time has passed for the initial fear to wear off. He can order them to refrain anyway, but it'll breed resentment and stress his authority over the borrowed units, which isn't worth it when he honestly really would like some air support against the barbarians. If they're willing to take the risks of pulling it off, best to ensure it's as helpful an operation as possible if they succeed.

The cover of darkness makes it a fair bit harder to spot the wyverns with the naked eye. Even night vision goggles don't solve that perfectly, though they're good enough that Civilization would have at least some advance warning. But what the darkness doesn't help with one iota is radar, and in fact they're aware of the flight almost as soon as they take off from their temporary aerie. 

The wyverns are objectively perhaps the most dangerous of the alien troops, at least counting only those they've managed to get a positive ID on, but by now that mostly means that dath ilan does not feel sufficiently secure to hold back and try to keep them alive. As soon as the draconic vanguard gets close enough, they're met with a coordinated barrage of wire-guided missiles against which their evasive maneuvres are useless.

How bad is it? They're prepared to press on in the case of casualties, but if it's devastating enough the rest of the vanguard might have second thoughts.

There is no rest of the vanguard. Not anymore.

...Oh.

It's hard to overstate how terrifying that is. It's not that wyverns or their riders are invincible, and in fact they often take significant casualties in internicine conflicts where there enemies know full well their strengths and weaknesses. But a blow this fast, and this total? It'd be surprising from an apostle, even if perhaps not quite unprecedented. Almost as one, all the riders lucky enough to have a position in the flights further back are going to turn around.

It's not going to be that easy. The first strike was their best effort, at the closest range from the best firing conditions with the most work done to prepare, but they were hardly engaging at the limits of their range either. They can cut a bloody swathe in the retreating riders as well, and where it's not lethal they can injure them enough to make any further fighting very ill advised. Round one against these creatures was bad, and now that round two is going their way they're going to ensure there isn't a round three.

It doesn't get all of them. Lesser or not, they're still dragons, and a clean sweep like the vanguard would take a similar volume of missiles or a lot of collateral damage. Fortunately for the Sadarans, they have neither, and the dath ilani barrage is not enough to kill most of them.

Unfortunately for the Saderans, it doesn't need to. A dragon rider is not a soft target, but almost all of that comes from their aerial maneuverability and the danger inherent in engaging their mount. Their armor is incredibly expensive, but mostly because of how light it is, and the threats it's supposed to war from them are lucky arrows and a near misses from enemy fliers. When pitted against point blank high explosives, it might as well be wrapping paper, and mortal flesh and bone are vastly insufficient to pick up the slack. The wyvern corps entered the battle a wounded beast, and left it a hollow shell of itself, with the now riderless vestiges following their luckiest counterparts back to what is hopefully some measure of safety. 

(Other wyverns scatter across the city, or are too injured to keep flying, or are so driven with rage that they spend enough time hunting whoever hurt them that a second round of missiles can take them down, but wyverns are very exactingly trained and these fill the minority of cases even now).

The person in command when news of the disaster hits the lines is not the Legate. Rank hath it's privileges, and among them in this case is the privilege of getting to sleep during the night in a real bed safely away from the barbarians. That role falls to Tribune Floros, one of the more senior staff officers, and as much as he normally appreciates the trust and honors that come from being a client of one of the Legate's closest allies, he is not prepared to handle this by himself. The wrong word to one of the surviving, battle-shocked aristocrats in the aftermath could see this turn from a barbarian atrocity to an unmitigated blunder, or worse yet an intentional plan by him or the legate, and the outrage that would evoke doesn't bear thinking of. The legate might survive a blow like that, but the same can't be said for him. His family is equestrians, for Deldort's sake - rich and well connected equestrians, certainly, but he doesn't have half a dozen senators and governors as cousins, and his name isn't on any of the earlier successes of this invasion either. So given that he has neither his commander's standing or charisma to help him avert it, he needs help from the man who does.

A runner to wake the legate, double time like you're being chased by hounds, and tell him it's an emergency. The tribune will be making himself busy in a way that doesn't risk contradicting whatever plan Cattaneo decides on. Starting with standing down troops - they weren't going to deploy the army even if things went perfectly, not with everyone settled into their sleep and how hard it would be to coral them back afterwards, but they did have some night-fighting specialist detachments standing by in case the raid was successful enough to make it worthwhile. That's definitely not happening now.

If you're waking him up in the middle of the night for this it had better be important, or so help him-

Well, that'll teach him to tempt fate. 

The legate allows himself a minute to boggle, in the privacy of his quarters. And then a second minute after. None of his first, second, third, or fourth thoughts are the sort of thing he can afford to project right now, and given the situation that trumps even the need for haste. Then he dons the mask of an unflappable general, and gets to work. They're to move the night fighters into the watch rotation, dispersed to prevent any cluster attacks, and when the sun comes up instead of encamping in place they're to head back for the gate. He's moving up the schedule so the legion won't be spending another night on this side, making them resting close to the front lines a needless risk, and he needs the gateway operating at full capacity come tomorrow to get everyone and everything back through quickly. As for the wyverns and their riders, no expense is to be spared on their treatment, including the intercession of his own personal surgeon. Each one that survives is another family he can sew up into helping cast the affair as a heroic struggle rather than a bitter enemy out for a pound of his flesh, at least if he spins it right, and despite the exhaustion his future self will thank him for putting in the effort to meet with everyone in condition for it. 

And someone get a wizard or a priest or a philosopher on figuring out what the fuck just happened to them, and if it's going to wreak similar havoc on the rest of his army tomorrow.

With the amount of surveilance they're doing on the imperials, it's not actually difficult to piece together what's happening, even through the cultural and language barrier. That's not to say that it's completely clear on the details - especially at first, it's not obvious if they plan to withdraw through the portal entirely or just further reduce their radius - but even the deployment of additional troops to the perimeter doesn't dissuade it once they can see where those are being reassigned from. Prediction markets on how much territotory they will control at various future timestamps start trading down quickly, and the estimates of the casualties to accomplish it trend down; the impact on more speculative future markets is smaller, but of course there's movement there too. Their logistics may be subject to bizarre constraints*, but it's not difficult to miss what the changing tempo and movement of resources to and through the gate means for their future, and from what they've seen it would be an expensive bluff to make.

*As with many parts of the invasion organization, the invaders logistics situation is incredibly baffling. It's not merely a question of being primitive, or even of being inconsistently advanced with dath ilani historical techniques, but indeed missing optimization that any eight year old out of civilization ought to be able to manage from a cold start. It's not impossible they're just not that smart, but it seems incompatible with their other achievements, since heritage optimization just isn't that complicated a project compared to the other humanoid variations they've demonstrated.

That leaves them with the question of what to do going forwards. The null action is of course to continue as they were; the plan if it hadn't been interrupted was a night attack of their own, to test if their (hopefully) superior low-light sensory options and ability to shut out the local light sources at will would allow them to get a decisive engagement with few casualties on either side. It's not a bad plan even now, with the updates to account for the changes in invader strategic posture, and on the margins moderately more likely to succeed with enemy air support as a smaller factor. And aggression has a lot going for it as well - if the invaders retreat safely through the gate and close it behind them, that leaves their only real source of information on how this happened coming from whatever prisoners they've managed to take, most of whom are presumably not specialized in genetic engineering or portal construction and can't be relied upon to have more than a layman's understanding of the subject. If that and whatever corpses and material they capture isn't enough to duplicate the work, in the best case that risks them leaving an unimaginably* enormous amount of value on the table, forever, and in the worst case gets Civilization is destroyed by another attempt having given up their only opportunity to prevent it.

On the other hand, weighing against those uncertain losses and gains are the very real and immediate issues of a lot of people dying, including true deaths. They're not going to underweight the possibilities here, dath ilan works very hard to be about to properly compare counterfactuals and only do time discounting when it's actually warranted, but it remains the case that - presuming that the withdrawal doesn't come to a halt if they reduce the pressure too much - the operation is no longer in service of the objective it was planned to fulfill, and at the very least that ought to adjust the risk-reward calculations here. There's a strong push to scrap the whole affair.

*Used here both in the sense that it's an enormous sum with too many moving parts along too many axes of unknown information to readily visualize, and also in the sense that saying this phrase aloud in dath ilan has the cached response "skill issue."

Are you really going to deontology this, now of all times? Sometimes you have to shut up and multiply, and even with all the uncertainty we both know what the markets are saying here about our expected outcomes if we leave them unimpeded.

Are you really going to give up that easily? I thought this was supposed to be an assembly of the greatest minds in civilization, but the best plan we can come up with for this has dozens of deaths priced in outside of the tail risks? 

I'm not saying it's easy. I'm saying it's our job to shut up and do the impossible.

...The odds of success are only marginally worse if we start it two hours later, accounting for the refinements we can make to the preparation. That's your deadline, then, to come up with a better plan or convince enough people the outcomes are better your way.

Dath ilan makes a science of doing the impossible. Not the logically impossible, which is an distinct word in baseline and wouldn't risk confusing a native speaker, but the apparently impossible, that which seems upon examination as though it cannot be done.

The thing about doing the impossible, and the part that makes achieving it impressive, is that you often can't do it. The fact that something seems impossible to accomplish isn't proof that it is, but it's quite good bayesian evidence that any solution is going to be hard or difficult to see. The potential rewards from some seemingly impossible things is sufficient to still accrue a large outlay of civilization's resources towards solving them, of course, but for every attempt that succeeds there are half a dozen more that turned out on closer inspection to have been accurately assessed even when pitted against a team of genius experts with copious incentives for success - it takes a lot for a dath ilani to declare something impossible in the first place, even in casual conversation. That doesn't mean there aren't any tricks to it.

The ideal method is to cheat. You can pick your battles, take on tasks where you have secret information or advantages, come prepared with more prep than anyone expected you to have done, and end up with a task that may well be very difficult to you and none other. In this as most cases, dath ilan considers cheating to be technique, and if it's sometimes a bit less impressive it makes up for it in ease and effort, but betting on a market that gives incredibly long odds against something happening it and then resolving it by their own actions is one of the archetypical impressive ways for a member of civilization to get rich.

There's probably a number of ways to do that here. The events of the past day have shown that many things they thought they knew about the state of the universe, and possibly the laws of physics that govern it, are wildly wrong, and where your map doesn't match the territory there are usually routes between points you cannot see. Many people are devoting their time to figuring those out, and if they can figure out how to make their own portals or whatever the trick is to this kind of bioengineering or whatever dealt with those helicopters, there's plausibly something applicable here. The problem here is that all of those are already being done by some of the brightest minds in civilization with enormous amounts of resources behind them, and coming in from a relatively cold start it's very unlikely that they'll be able to both pass them by and get it done fast enough to matter. The linguists have a rather simpler problem, in that there's is one that has been extensively prepared for with tens of millions of hours of labor in advance, but whatever simple structures underlay the emergent complexity of alien communication have proven difficult to derive and their example corpus leaves a lot to be desired. Absent a low probability development there, this method won't do them much good in the timeframe in question.

What, then, to do? 

It's a well understood phenomenon in dath ilan that, once something has been accomplished once,accomplishing it again is typically simpler. Not just because they were able to learn from the previous attempts, either - knowing that a problem can be solved, and under what constraints this was done, is itself large amounts of data about what the solution has to look like. If you learn it is possible to build something in 10 hours, you can discard offhand all the search space with longer duration; from these and other details, it is often possible to figure out in broad strokes what the solution must have looked like for it to have been solved. If attempting to solve a problem normally involves first determining what you have, and then what you want, and how to use the former to achieve the latter, this involves looking at what success will look like, and determining what must have happened to achieve it. If something possible seems impossible, then that is not a contradiction, but a sign that somewhere important your map does not match the underlying territory. You need merely assume that a way to win exists, and if necessary reframe success and the material conditions until one pairing matches a way forwards. It can be a dangerous epistemic state to try and stay in for too long, even for a trained inhabitant of civilization. Sometimes there isn't anything wrong with your map, and there isn't actually any limit to how much you can throw away in pursuit of such a strategy if you're wrong enough about how the world works. And it's far from the only method, with dozens of other commonly used reframing schemas existing. It's just good enough to often see use regardless, and this is one of those times.

So what's their goal, then? To remove the invaders from the city without more true deaths?

No, that's both over and under-specified; it demands both too much and too little here. And also missing the point of the deadline. They don't have to solve the problem in a handful of hours, they have to make it seem likely enough it's solvable their way that the timespan is extended.

That's not exactly helpful, though. Saying your goal is to convince someone you can accomplish a task usually still involves you being able to articulate what you're planning to accomplish.

Which is why they're going to hold off on proposing solutions, even for what the goal looks like, until they've actually thought about it for 15 minutes on the clock, and then write down the ideas they have and share them to avoid initial cross contamination. Ideally you'd spend longer than that, but the timeline is short enough to rush things, and better to halfass everything than do this part properly and need to quarterass the rest of it from time overruns.

After the brainstorming and ensuing discussions, a few potential outlined goals take shape across the different subgroups they shuffle between, which eventually synthesizes into one with minority dissent.

"We will know the operation succeeded when neither Civilization or any constituents thereof are under a threat that could be meaningfully ameliorated by attacking the invading troops, and the standard for a flawless success is that no one truly dies accomplishing it."

Put that way, it's clear that the whole business of needing to force the troops back through the gate is a limited one. Not because it wouldn't work at accomplishing those goals, but because once you start actually thinking about it like a riddle it's obvious what other kinds of solutions could work there. They could take the gate itself instead of pushing troops through it, and fortify it. It's much more obvious how to non-lethally keep people from storming a position than to dislodge them from one, though taking the structure without casualties won't be trivial; with fortifications inside and out of the ring, absent additional capabilities there wouldn't be more threats to dislodge. They could seal off the portal without taking it. It would be more difficult, in the face of the demolition techniques the aliens have thus far demonstrated and any more they might keep in reserve, but rendering a place approximately impossible to traverse is not actually beyond their means. They could simply retreat. Losing Schelling Point would be a very expensive blow, but there's a lot of expensive things that are worth doing if it saves enough lives. They've seen how quickly the aliens can take ground when advancing unopposed, and it would not actually be difficult to keep people away from that for weeks while they work on better solutions without even needing to fortify, especially now that the first combats have given everyone still in the city time to escape.

"Or, you know. We've seen what they prioritize when able, above killing or capturing prisoners or almost anything short of immediate strategic objectives, and there's one kind of exchange you don't actually need much of a shared language for. What's stopping us from bribing them?"

That'd be giving in to threats.

That's deeply unclear. It's not obvious what parts of this course of action they expected to benefit them and how it weighs off against costs, much less that they did it specifically expecting to be bribed to leave in a way we don't want to incentivize. Decision theory says you shouldn't let yourself be exploited, sure, but it doesn't mean you're obliged to blow yourself up whenever you're confused. Besides, how much would you have been willing to pay if they'd negotiated opening a portal in advance, conditional on believing it? Ignoring the killing you'd have made on prediction markets from being the only one to know it was going to happen, I mean.

Division of labor, then. One group will get the balls rolling for prep work on these plans, creating the necessary inventory list and filling out documentation and setting up the prediction markets so they can go live promptly, while a second group consisting of the people who aren't necessary for that goes back to think of alternatives or refinements. They're not expecting much out of it, not now that they've already done a whole effortful team planning session, but it remains the case that it's often worth taking unlikely bets when the potential payout is large enough and this qualifies.

The only real refinement ends up being that they can potentially deliver a lot of payloads by ballistic arc if they get the right launchers in place, which is pretty much inherently going to be less accurate than the drones but hedges against a repeat of whatever took down the manned helicopters. Mostly they end up thinking of specifications for possible products that probably don't exist but would solve things if they did, like some kind of distance-deliverable concrete spray to render the gateway impassible; the vaguely plausible ones they take a moment to specify enough that they can post a bounty on it to the net in case someone happened to have it in their back pocket.

And then the third team - or perhaps more properly a half dozen teams, each split up by which plan they're on and who they're talking to - sets out to pitch the emergency services and the public on their ideas. They're in competition to each other to an extent, but for the most part they'd all prefer the other plans win over people instead of status quo ante, and many of the exceptions are still willing to work together if it still means better odds their own plan (here referring to the plan they champion, which everyone involved has done their best to decide for reasons other than who first proposed it) gets traction. In another world they might be worried about accidentally locking things into place with decision paralysis, but Civilization works hard to keep their decision-making infrastructure robust against that sort of issue.

We're not saying no, but we're not saying yes either just yet. It's not that we don't appreciate last minute arrivals with a plan to fix everything that nobody else thought of, we're still human, but this is serious, so let's talk specifics here. How long will each option take, 80% and 99% confidence intervals? What estimated risks are we taking into account, at what rates, for what payouts? Give us some specifics we can use to evaluate tradeoffs once we run prediction markets to double check your numbers.

They've got those prepared ahead of time, of course. (It's facially obvious that you would need those, even six year olds know better than pitch ideas without numbers, though this level of sophistication usually comes later).

An air raid with commandos on the gate structure would take a few hours to arrange, and is not really a novel strategy here except for implementation details, so they can borrow numbers from some of the extant markets as a baseline. They'd be risking the deaths of everyone dropping in, plausibly including their true deaths, and any pilots involved, plus a number of casualties among the defenders if things went wrong, but significantly fewer if things went right; and there are a number of potential problems that could come through a gate that are readily resolvable via people on the ground ready to deal with it and not otherwise. For their preferred version mean projections are about 17 paratroopers dead and four times that in defenders, about 2 and 6 of which are true deaths; the median case is about 7 but 80th percentile version is about two dozen* and 99th percentile is hundreds dead. Here's three other plans elsewhere on the pareto frontier and why they picked this one, presented in case someone has a compelling case on the tradeoff they didn't see. Yes, it's more casualty prone than the already rejected aerial missions it's being compared to, but they're pretty confident it would kill significantly fewer aliens and that's worth it. If Civilization survives this coming year, they're confident it'll be willing to pay the rates it would take to match people's cheerful price for the mission in order to save that many lives; it won't be able to make that trade then unless they can close that deal with their future selves now, which means there's a sizable amount of value up for grabs here. They've got a growing list of investors who agree with them and are willing to buy shares in the value Civilization will later pay out at the following rates, and while it's not enough to fund things yet emergency services won't have to take on all the risk.

*3 groups of 8 in baseline, technically.

Just attempting to do area denial on the gate and its surroundings is significantly lower investment, and could be done inside an hour (from now, not from when they first started getting prepared for it). A lot of the necessary work to make it go well is already in place among the various military forces in Schelling point right now, and there's also less people at risk from the operation. Their median and modal case projections are both at zero dath ilani casualties, and even taking into account the 99th percentile outcomes where it provokes a response the estimated casualties above replacement doesn't pass four. However, it's inherently harder to be careful when you're fighting at that kind of a remove, so the estimated risk profile for the aliens looks roughly similar to an airdrop, and it's significantly less resilient of a strategy. Especially so in the case of unknown unknowns, since having humans at the front will go a long way in terms of providing them with options, but outside of that too. Even if they bring out the really scary stuff like napalm or turn the whole area into an impassable resiny mess or bury it in rubble, it wouldn't keep determined humans out long term without constant upkeep; their counterparts are too capable for anyone to want to rely on their bizarre logistics issues generalizing.

And then bribery is, of course, both the biggest and least risk. The least risk, in that even the worst case scenario has between one and three people in danger and their estimates of any death are low enough that it doesn't even make the 99th percentile estimations. Capture and imprisonment seem possible, of course, but it's not difficult to find qualified volunteers who don't consider that particularly aversive. And perhaps more encouragingly, unlike either of the other three options at hand there aren't any anticipated deaths if things go as planned.

And the most risk, in that it doesn't actually guarantee anything. It's that same fact which so consumed their debates and kept it from being adopted as the consensus platform; as much as it would unarguably be amazing to resolve this without any further conflict, but there's a lot of places it could go wrong in a lot of different ways. They could seem like a trap, and fail to so much as get a meeting. They could be wrong about what their counterparty values, and fail to successfully offer anything, or succeed too much and convince them that attacking dath ilan is more rewarding than previously imagined. They could be entirely mismodeling the alien psychology at work here, or dealing with a scenario where contrary to appearances the decisionmakers behind the invasion are not approximately far mental-distribution humans, and simply fail to communicate the attempt at all. And of course there's the possibility that time doesn't actually favor them. They think it's more likely than not it does, and the markets* seem to agree, but it's far from a sure thing, and they could very well end up frittering away what advantages they have in the conflict beyond their ability to regain. Right now, as bad as the invasion is, it's still looking like one of the absolute best case scenarios for getting attacked by surprise by an enemy with superior capabilities; just because they regularly rehears what to do in the case of alien invasions doesn't mean anyone in dath ilan is *unaware* of what the expected outcome is if that actually happens. It's a reference class that includes a billion deaths as table stakes.

A lot of the worst possibilities would end up that way with most of the other plans, and some might get uniquely disarmed here. But everyone involved would really prefer there was less superheated uncertainty about literally everything.

*Markets of this sort use a somewhat different method than normal prediction markets, since anyone who thought civilization was underrating the chance of their defeat wouldn't expect to collect their winnings. Instead there's a proxy based on the current bond rate, where people who expect the world to end can take out loans to spend now, and repay if their prediction is falsified. It's better than nothing, but there's enough confounders that people tend to have less confidence in the results, especially over very short time horizons.

 ...They're gonna have to think about this, though to preserve option value they'll parallelize as much of the prep work on their end as possible.