Explanation: In the spirit of total dipshittery that fascist regimes are known for, the Nazi forces in 1941 decided they would betray the Soviet Union, recently their ally of convenience in destroying Poland, and launch a surprise attack in the summer. Sensible enough, invading in the summer, right?
Well, the Nazis expected to win the whole fucking war inside of six months (with Hitler predicting victory inside of three months), and so brought no winter equipment. And as the fighting intensified in the coming four years, they had trouble supplying their troops with even their ordinary needs, much less being able to supply them with good winter gear. So a lot of Nazi popsicles were left on Soviet land, even before the Soviets began to push the fascist cretins out.
Good riddance to bad rubbish.