So I am currently playing as Epirus and have done quite well keeping my original elephant unit alive... that is until I sieged rome and dealt with two full stacks of Romani. It was my own fault that I wasn't paying enough attention to see the equitites companion cavalry come out of no where and nail my elephants with their javlins... so I lost all but two and ended up have to kill them myself because they started to blink red. After the battle which I won I got all my elephants back.. they all healed. Am I just lucky?