Kobolds are pesky critters who live mostly underground. Their preferred habitat is a mine dug by other people, because mining is hard work. Goldshire has a lot of mines, because of all the gold. Hence, y'know, the name. There are several that have been tapped dry, and therefore are attractive to kobolds. Normally it's the job of the Stormwind Guard to patrol these abandoned mines regularly and keep the kobold presence down to a level that won't affect the villagers. However, the Guard has been stretched thin of late, doing who-knows-what at the whim of various nobles. To make up for this, a militia has been organized, consisting of grizzled old veterans too old for active service and eager youngsters who want something more out of life than the same boring job as their parents.
The target of choice today is Echo Ridge Mine in Northshire, one of the oldest in human lands and fairly swarming with kobolds. They're not much of a challenge for even the inexperienced adventurer, but if you're not careful, one can get up close and BONK you right on the head with a crude club.
As just happened to Theriel.