IIRC, most cities of the Empire have a Dwarven Quarter. Dwarven skill in metal working and stone masonry outpaces the vast majority of Empire craftsmen so most cities in the Empire, especially wealthy ones, do what they can to vie for the attention of Dwarves willing to relocate from their mountain holds. Given enough time, these Dwarves come to see the Empire as their home, albeit a temporary one most likely, and will fight in its defense.