Blitzkrieg

Blitzkrieg or lightning war was a method of warfare developed by the Germans and used during World War II. It relied on speed and surprise, with deep penetrations by columns of tanks and air support by dive bombers.

Blitzkrieg attacks could easily be defeated by coordinated counterattacks at the base of the armored columns, but it wasn't until the middle of the war that the Allies learned to use a mobile reserve effectively and to do this.