They were just about to get up from the water, so I reckoned a charge at that time would be devastating as they didn't have their formations ready, sort of. But instead, the unit just ran down in the water. It was a set of 3 fresh units. And they DIDN'T have the swim ability. I thought the logical thing would be to stop just above the water line and kill the incoming enemies, but no, they decided it was best to suicide charge down into the water...