Hitler locked himself in his bunker and lived under the illusion that he was winning...that helped him lose...he thought he was winning...so used tactics winners would use...etc...

Napolean had something wrong with him that meant he went to sleep randomly...I can't remember what it's called...he often fell asleep during battles...and so couldn't order retreats etc...

If you want a military genius...look at Alexander the great. THERE is your military genius.

If you don't want to...then just look at the famous figures in historical periods - the Egyptians, Greeks, Romans etc...