The kings came and fought; Then fought the kings of Canaan. In Taanach by the waters of Megiddo: They took no gain of money.
"The river Kishon swept them away"  (Judges 5:21).  Anyone familiar with what horses will do in the face of a hailstorm could have no trouble envisioning what happened.  The direction from which the hail came determined the direction in which the stampeding horses moved, and that propelled many into the turbulent waters of the flooding Kishon, or into the mire of the flood plain.