This is why there should be an option to Pillage as you move, in order to simulate that kind of warfare. Thoughtout the course of a month, an army should be able to rape and pillage as they engage local defense and defensive positions.
Yeah, I've been playing Ermor AE in a SP game. Conquer a povince, crank the tax rate to 200% to piss-off the locals, then pillage and patrol it down to 0 pop. Really gets the income going.
Ermor AE seems too easy against the AI. Of course, I've only been playing the full version of Dom2 for acouple of months, so right now I have all of the AIs set to normal.