
This can be bypassed if you manage to kill the factions' leadership before attacking the city, through either open battle or assassination. If you manage to seize a faction's capital city before pacifying the rest of their empire, a fairly large army consisting of late-game units with full armor upgrades will spawn in, take back the city, and then go ransack the rest of your empire.

Certain AI settlements will spawn reinforcements when attacked, discouraging opportunistic sieges with small/weak armies.

Most of their units are on-par with those of the Elves.
