Hitler’s invasion was behind schedule because he had to deal with problems caused by Mussolini’s failed attack on Greece, which exposed the German’s southern flank to British air bases. Hitler then had to send troops to the Balkans to take Yugoslavia and Greece, but this delayed his attack on the Soviets.
Approximately 4 million axis soldiers invaded the Soviet Union at the time. Hitler’s three pronged attack focused on invading to the north, center, and south of Soviet Union. This was the largest German military operation of WW2. The attacks were aimed to weaken Russia. There were attacks on Stalingrad, Leningrad and Moscow. Hitler stabbed Stalin in the back by invading Russia. He had said that it was a defensive attack to justify his battle but it was clearly offensive. Hitler invaded Russia primarily because of his belief that the Slavs were weak, inferior people that deserved to be subjugated(under complete control of Hitler).
Nazi Germany launched an attack on the Soviet Union, and it consisted of of 180 divisions, including 20 panzer divisions, 8,000 tanks, and 3,200 airplanes. German troops were stretched out along an 1,800-mile front. The Soviets had 160 infantry divisions but were able to mobilize another 300 divisions out of reserves within half a year. Hitler miscalculated the power of the Soviets. Due to an early winter and some Soviet resistance, the German army came to a standstill. Even though the temperature was 30 degrees below zero, Hitler refused to retreat. Many soldiers deserted the army and others started to disobey many direct orders. By December 1941, Hitler decide to declare war on the United States which probably made his defeat inevitable and turned the European conflict into a global one.