barely kill anyone O.o

im taking on spain atm in spain, and i just won 4 battles at the end of turn by defending and putting my motars at the back of the map, having them constantly killing the whole battle, all 5 units of motars in that army are up to like 3 xp now and are getting hundreds of kills per battle. particularly good for wiping out cavalry and generals :D sure they miss alot but if they land and explode in the middle of a unit they can kill 10-20 guys