Feature where all non-casualty units have the option to retreat prior to defense roles.
example. attacker moves into territory and proceeds to role. He successfully hits with X roles. Defender chooses his casualties (X) and submits his entry. System prompts to ask him whether surviving troops (Y) will remain or retreat. If he chooses to remain all units (X+Y) get a defensive role. If he chooses to retreat only the casualties (X) get a defensive role. All surviving units (Y) forgo defensive rolls in order to vacate the territory.
I've brought this up before but it seems to bet met with little in the way of explanation as why this is do-able or not,or why it may not be a desirable feature. It seems to me like a real improvement to the depth of the game.