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.