> Realistically soldiers should head in the right compass direction and hope for the best. But then you (the player) shouldn't have a proper map of your own, either.

It would depend where and when. An army on their own territory might know the terrain. An army on enemy's territory would try to send scouts ahead as opposed to wondering randomly, too.

So at the army level it would almost work out like the they have "psychic" powers because they have scouts. At the individual units it would depend. But it would also be kind of annoying to play if the realism is increased too much. Like they wander into the woods and get stuck in a bog and die of hypothermia.