It'd be cool if you had something similar to that (caravans full of extra food) that existed army-wide. For example, say you've got an army invading a starving region. Get a few of the troopleaders to drag along caravans of food, sit in the region as normal, provisions begin to run out. Except when they do, they'll automatically replenish from friendly food-carrying caravans in the region. Baggage trains, ftw. Caravans would slow people down considerably, but give some tactical advantage.
