A German soldier tossing a stick grenade at Soviet troops during Operation Barbarossa
Blitzkrieg, meaning "lighting war", was a tactic employed by Nazi Germany during the early years of World War II (1939-1941). The tactic was advocated by panzer leaders Erwin Rommel and Heinz Guderian, and it involved the use of larged armored and mechanized spearheads with close air support in a revolutionary new form of armored warfare. Tanks and mechanized infantry would assault the enemy formations and punch holes in their lines, with the Luftwaffe air force bombing enemy hardpoints to assist in the advance of the ground forces; the Luftwaffe would also bomb enemy airfields to ensure that it had complete air superiority. The blitzkrieg tactic was successfully used during the 1939 invasion of Poland, after which it became a major German tactic during its conquests early in the war. The Netherlands, Belgium, France, Norway, Yugoslavia, and Greece would be conquered using the tactic, while it initially worked very well during Operation Barbarossa, the invasion of the Soviet Union in June 1941; only the winter and supply difficulties would stop the Germans from taking Moscow and possibly winning the war. After the summer of 1942, Germany was put on the defensive, ending their blitzkrieg campaigns. However, Japan would employ the tactics during its "Oriental Blitzkrieg" from December 1941 to June 1942, quickly overwhelming Hong Kong, the Philippines, Malaya, Singapore, Burma, the Dutch East Indies, and several Allied islands in the Pacific by using similar air-ground coordination tactics.