Who was Himmelstoss? Why did Paul, especially, remember him?

Corporal Himmelstoss

Like Kantorek, Himmelstoss is in just a few scenes, but he is an important representative figure. As Paul's friends see it, Himmelstoss epitomizes the way men with little power otherwise--Himmelstoss was a postman before the war--exploit whatever power they gain in the military. A ruthless disciplinarian in the training platoon Paul and his classmates originally joined, Himmelstoss delights in humiliating the inferior-ranking soldiers, especially Tjaden. However, even a coward like Himmelstoss can be redeemed by the camaraderie of war; after he is brought up to fight and has his first experience in the trenches, he makes up with the men he previously punished and insulted.