In the early battles of Second World War, German forces had gained notoriety for the rapid and successful invasions of Poland, the Netherlands, Belgium and France, and the Soviet Union, in 1939–41. Although the early-war Panzer II, III, and IV were clearly inferior to some of their French and Soviet counterparts, this blitzkrieg (‘lightning warfare’) was made possible by training and organization, integrated communications with the combined-arms employment of integrated infantry, armoured forces and aircraft.