Having signed a non-aggression pact with Hitler only two years prior, he did not want to believe a betrayal was possible.
A fierce battle in the winter of 1941 to 1942 pushed the Army Group Center from Moscow. This occurred for two reasons. First, following the invasion, Soviet leader Joseph Stalin was despondent. Having signed a non-aggression pact with Hitler only two years prior, he did not want to believe a betrayal was possible. Therefore, Stalin retreated to his Dacha on the outskirts of Moscow in a state of denial. However, he remerged in time for the November 7th Revolution Day parade. This celebration lifted the spirits of the Red Army and the Soviet citizens, giving them the willpower to push out the Wehrmacht. The second reason for the German defeat was Soviet General Georgy Zhukov. At the beginning of the invasion, Zhukov was stationed in the east fighting the Japanese. After beating them in the Battle of Khalkhin Gol, Zhukov then came to the European front, thereby organizing the defense of Moscow and playing a significant role in defeating the Germans.