PANZER IV TANK. During World War II, the use of tanks revolutionized the way war would be fought. It was known as “Blitzkrieg”, and the German Panzer tank was the key vehicle in this new style of war. The Panzer medium tank had a number of major modifications during the course of the war. The MK IV featured a 75 mm main cannon and two 7.9 mm machine guns. However, the MK IV was not heavily armored and suffered greater losses as the war developed. The PZKW was conceived in 1934 and went into lim