Seems to me M2:TW got it reversed, I thought it was typically only the nobles who were kept alive so they could be ransomed, sort of a unspoken courtesy between rulers. If that was correct, FM's would be captured and ransomed rather than the army. How I wish they had implemented that. Maybe some historians can comment on the classical period, but I think that for the most part enemies that surrendered would most likely be disbanded and returned to the now subjugated population, I don't think they had POW camps. Those who ran would be killed. Maybe if the general felt the enemy had committed some especially heinous act, he might offer no quarter. I don't think M2:TW system of releasing and ransoming is especially realistic.