Operation Barbarossa (German: Unternehmen Barbarossa) was the code name for Germany’s invasion of the Soviet Union during World War II that began on 22 June 1941. Over 4.5 million troops of the Axis powers invaded the USSR along a 2,900 km (1,800 mile) front. It was the largest military offensive in history, and as well as the large number of troops it also involved 600,000 motor vehicles and 750,000 horses. Planning for Operation Barbarossa started on 18 December 1940; the secret preparations and the military operation itself lasted almost a year, from spring to winter 1941.
Barbarossa’s operational goal was rapid conquest of the European part of the Soviet Union west of a line connecting the cities of Arkhangelsk and Astrakhan, often called the A-A line (see the translation of Hitler’s directive for details). At its end in January 1942, the Red Army had repelled the Wehrmacht’s strongest blow. Adolf Hitler had not achieved the expected victory, but the Soviet Union’s situation remained dire. Tactically, the Germans had won some resounding victories and occupied some of the most important economic areas of the country, mainly in Ukraine. Despite these successes, the Germans were pushed back from Moscow and could never mount an offensive simultaneously along the entire strategic Soviet-German front again. Read full wikipedia article.