In a "blitzkrieg" the attacking motorized infantry armies move quickly, and are helped by tanks and aircraft. Enemy slower moving units are overrun or surrounded. They are often captured with little fighting. Often the slower units become disorganized and are not yet ready to fight when they are captured. Also blitzkrieg is a way to disorganize the enemy The strategy of blitzkrieg  was developed in the 1930s. The Wehrmacht seldom called it by that name.