Every village/town/city in Overthrow has a current level of "Stability". It represents how the citizens feel about the faction who currently owns it.
= percentage of happiness with the currently owned faction (the OF, or RF)
+ Deliver medical supplies
+ OF patrols through town (if RF support is < 75%)
- Gunfire/explosions in town
-- People dying in town (not civilians, any side)
--- Killing civilians
Tax is paid to the owning faction according to stability. 0% stability = no tax. This is separate to Support donations, which are paid regardless of the faction owning the town. Big towns/cities will pay the most money, much more than donations, making the bigger towns much more important targets.