Many of the towns in Vestitas can be captured as a result of engaging with the adventures associated with their hex, as often the town government is in on or targeted by whatever conspiracy is afoot. When that doesn’t happen, however, characters may capture towns with pure military force. This requires two things: To clear out the current forces holding the town, and to install new ones behind.
Every hex encounter town in Vestitas is held by three forces. For the Imperium, these forces are the PDF, the Ecclesiarchy, and the Arbites. For Chaos territory, these forces are the Red Guard, Chaos sorcerers, and the Praetorians. Every town has a single squad of PDF/Red Guard with a chimera, an Ecclesiarchy preacher or Chaos sorcerer, and a pair of Arbites or Praetorians, plus the Lord Mayor, who is either a noble or a warlord. Once the first three (PDF, Ecclesiarchy, and Arbites or Red Guard, sorcerer, and Praetorians) have been defeated, the Lord Mayor will flee, although if he ends up being killed in the fracas, that works too.
Either way, once the players have cleaned the town out, they must drop a squad of at least a half-dozen of their own loyal minions on the town to provide the muscle. Providing a spiritual leader and someone to investigate crimes that dumb-as-bricks paramilitaries can’t figure out is optional, but encouraged.