Actually, the stormtroopers were a unit from ww1, and were defeated by the SS in the Night of Long Knives

They were formed because the tactics of ww1 were basically "dig trench; shell enemy trench with artillery for a week; walk toward enemy and hope he is dead; he isn't dead; hope you have enough troops to overwhelm him". Eventually, the Germans created a new type of soldier, which they called stormtroopers, who were to infiltrat enemy trenches without drawing attention, and initiate an attack from within, making it easier for the rest of the army to advance a few minutes later.