Why did Germany lose WW2? I agree with the answer one. Operation Barbarossa, which is the invasion on Moscow, was critical to the victory of the Nazis. The Italians failed to contribute enough to the Axis war effort, failing the invitations to Greece, Yugoslavia and the North Africa. The Nazis were forced to step in and delay that critical operation. Hitler planned for a four-month long war with the Soviets, avoiding the Russian winter, but by the time of the delay, winter is coming and the Nazis clothing is inadequate. Autumn rains made roads difficult to travel on, slowing down the military vehicles advancement. German’s strongest strength is in its mobility, which lost out to the might of the Russian railroad. Then Nazis will get annihilated in the winter and the rest is history.