Napoleon had made the same mistake and faced the consequences. He went into Russia with a force of 5 hundred thousand men and came back with only 5 thousand. Hitler in his ignorance did not learn from the past and make the same mistake. His forces entered Russia in summers and kept advancing. Russia on the other hand kept on destroying everything that stood in Hitler's way.
The Germans kept on advancing till they reached Stalingrad almost the middle of Russia. By the time the Germans reached Stalingrad it was already winters. The Germans had never seen so much cold. Same had happened with napoleon. The cold kept on jamming the German guns and on the other hand Russians kept on deploying snipers and riflemen on the field and finally the Germans were defeated heavily.
