At normal level, you can see who is not active...and perhaps do something about this. At Veteran level, the game does not indicate which leaders are going to be inactive for the turn of play. This is to prevent clever fox like players from "fixing the problem" by using more than one leader per stack.
I was a real soldier once. If something gets between me and tomorrow, then you can bet that you will see me tomorrow.
I'm the 51st shade of gray. Eat, pray, Charge!