[johnarryn]

Elephants will indeed trample your own troops as they retreat, although they dont do as much damage as when they are on the attack since they retreat in a straight line. Nevertheless, i often group archers and fragile mages slightly away from the center to give my elephants a clean line to rout through should they retreat.

As some other people have said, mixing elephants with high morale units is a smart move... doesn't matter much if the units can keep up with em, as long as theyre in the same unit.