might add a nice dynamic to battles if any reinforcments get unlocked by a certain timeframe.
lets say a 200man army gets reinforced after 15%of reinforcement time, then these 200men have to hold out until 15% of the battle time are over, at what point the reinforcements arrive.
nothing great, but a small n nice detail.
kind of a nice element if an underequiped army suddenly gets plated knights support n shit : )