Alexander.Baracca said:
Do note that in each city there is a NPC that tells you what is being attacked/defended at any given time.
This can be pretty useful but most of the time I don't even bother with it because you have to many varibles to search for. You have to pick the nation AND which specific regiment you want to check up on each time, and there's that lag going between screens. The information you get is also based on your nations standing in the war.
IMO Campaign battles almost seem to be random so what I do is just HP in Windurst [S] and look at the region screen and goto anyone with the little sword icon. If/when it's over I just warp back and pick another one. Me and a LS friend used to do that and just jump between zones all day. Sometimes we'd get in on a short one, sometimes we'd get a long one, but it was easier and more fun to do that then to try and analyze where to go next.