The origin of the war hammer is quite obvious. Essentially a hammer on a pole, the war hammer could range in size from two to six feet long, and was great for making a large-area impact. This was necessary because armor got to be so strong at critical points that it was hard to break through. A blow would simply bounce off of the curved shape. With a war hammer, a knight could get a concussion right through a helmet, without the war hammer actually piercing it. Later, a spike was added to the back side, to allow thinner armor to be pierced.