The Battle of Moscow was a military campaign that consisted of two periods of strategically significant fighting on a 600 km (370 mi) sector of the Eastern Front during World War II. It took place between September 30, 1941 and April 20, 1942. The Soviet defensive effort frustrated Hitler’s attack on Moscow, the capital and largest city of the Soviet Union. Moscow was one of the primary military and political objectives for Axis forces in their invasion of the Soviet Union.
Initially, the Soviet forces conducted a strategic defence of the Moscow Oblast by constructing three defensive belts, deploying newly raised reserve armies, and bringing troops from the Siberian and Far Eastern Military Districts. As the German offensives were halted, a Soviet strategic counter-offensive and smaller-scale offensive operations forced the German armies back to the positions around the cities of Oryol, Vyazma and Vitebsk, and nearly surrounded three German armies. It was a major setback for the Germans, the end of the idea of a fast German victory in the USSR.