I haven't been using cavalry much. When an AI horde of 300+ troops turns up, cavalry seem wind up getting tangled up into the infantry battle even if orders are set to attack archers/rear. They seem to work better in smaller battles.
I've had more success with archers set to "fire archers", as long as they're set way behind my regular infantry. Otherwise they charge forward to get into range and wind up in front of my infantry and get eaten
