The German airplanes and tanks started the attack on the Soviet Union. The Soviet Union was nowhere near as prepared as Hitler's army. Hitler's army was prepared with weapons and were well trained that was not the case for the Soviet Union. They did have a fairly large army, but didn't have the amount of weapons or the training compared to Hitlers army. As the Germans got further into the Soviet Union they realized that the Russians had use the scorched earth policy.
Which was when they burned and destroyed everything, so that the enemies wouldn't have any place to stay or food, just like what they did with Napoleon. The Germans bombed the warehouse where the food was stored. People were so hungry that they started eating anything that they could find which included rats and crows. Around 1 million people have died in the winter of the city Leningrad. The city still didn't fail, so next Hitler went to the heart of the Soviet Union which is Moscow. The Germans were not prepared for the cold Soviet Union winter as they were wearing summer clothes and the temperatures got lower and lower. The German soldiers obviously didn't pay attention to Napoleons defeat about 130 years back. Hitler still said "No retreat!" The German troops kept going into Moscow which did nothing for them besides losing more and more of their men which added up to 500,000 lost