Frankly, I don't think I have yet even seen a unit withdraw from combat, and the "Flanking" promotion, which adds a meesely +10%, would only be useful in vanilla with units like Cavalry that already start with a 30% chance to retreat. Also, which units have a (decidedly miniscule) chance to retreat, and which done, doesn't actually make much sense: why do CATAPULTS get a 20% chance to retreat, but horse archers get none?? I think that mounted units' ability to flank and provide support, as well as archery units ability to act as support and skirmishers, should be better represented in the game, for a better gameplay feel if nothing else. The simplest and most obvious way to do this would be to bump up certain mounted units' withdraw chance (by about 10%-20%, depending), and give archery units an inate chance to withdraw as well... maybe have some gunpowder units as well. However, it doesn't seem very realistic for longbowmen to be able to retreat from riflemen; nor for a knight, with his heavy armor, to escape the range of a longbow; nor for crossbowmen to outrun horse archers. It also wouldn't make sense for an archer to be able to withdraw from fighting a tank. So, I was wondering, would it be at all possible to give certain units a withdrawal chance, but have that chance be negated when combating certain other units-types (UNITCOMBAT) or unit-classes (UNITCLASS)? I think that this would allow for some realistic and balanced parameters for withdrawing from combat, which to my mind seems sorely underrepresented in the game.