1) Germany invaded the Soviet Union in 1941 underestimating their abilities, leading to the failure of their Blitzkrieg strategy and the beginning of the end for Germany on the Eastern Front. 2) The US entered World War 2 after the Japanese attack on Pearl Harbor in 1941, allying with Britain and the Soviet Union against the Axis powers. 3) After victories in North Africa in 1943, the Allies invaded Italy but faced continuing resistance as Germany sent troops to rescue Mussolini.