I think you will always have up-to-date info on the changing borders of all the countries and territories as land changes hands, as it should be. Like others have pointed out, by this time news of that sort would make its way around Europe within six months (the time elapsed per turn). However, I think the actual fog of WAR will stilll be in effect; that is, you won't be able to see troop movements of other countries unless you have eyes on them (agents or military units of your own within the vicinity).

I wonder if supply lines will be dealt with at all. It seems to me that much of the warfare in this period involved maneuvering around your enemy to try to cut off his supplies, and generally avoiding actual battle where possible... but then, my knowledge of the period isn't great.