[General Tacticus]

To make swamp survival useful, you need a region full of swamps, not only one swamp here or there : those are easily crossed or avoided. Then you need to make sure there is something worth it inside, or people will just stay clear and do their fighting elsewhere...

I think all survivals should be made more powerful, actually : as it is they never factor in my decisions to hire a particular troop. If troops with swamp survival did not need supply at all in swamp, for example, then they would be worth looking for...