Whilst doing a PvP, my undead archer unit got attacked by a single division of human LI's. my front ranks were well prepared to intercept within a couple second if my undead archers had retreated into them. instead, against a single division, rather than flee backwards, they fleed directly forward into the LI division and the rest of the human ranks.
I'm aware of there being some issues regarding retreating when faced with multiple divisions, but this was the first time I've seen one battalion cause it for only one other battalion.