[Baalz]

At the point that you're describing the damage is already done so there's not too much you can do once you've already got unrest jacked up all over the place. Offense is a good option, but really what you want to do is stop the raiders. This can be easier said than done, but if your opponent is in a position to raid aggressively indefinitely it's going to make winning the war a very difficult prospect. Ambush his raiders, research anti-raiding spells (remote attack, teleportation, etc), send mages out to support your PD, and make it uneconomical for the raiding to continue on a large scale. The flip side, of course, is to raid him even more than his is doing to you. To a fairly significant degree managing raiding and counter-raiding is what wins most wars.