The German invasion of the Soviet Union had been a certainty for Adolf Hitler for a long time. Advancing to the east meant Lebensraum (space to live) for the Germans to him. Hitler had already described this idea in his political work Mein Kampf. In his opinion, Germany was overpopulated and the nation needed more territory. He wanted to find this Lebensraum in Poland and in the Soviet Union. The Bolshevists were his arch enemies and he therefore considered the Soviet Union a more important goal than Great Britain. The Germans lost the Battle of Britain but they opened a new front in the east nonetheless. This two-front war was to prove fatal for Germany later on.
Shortly after the plans to invade Great Britain were postponed indefinitely, the O.K.H. (Oberkommando des Heeres, Supreme Command of the Armed Forces) began making preparations for a plan to invade the Soviet Union, called Fall Fritz. Generalmajor Friedrich Paulus (Bio Paulus), future commander of 6. Armee, was one of the first officers to start working on the plan. The operation was to be launched in the spring of 1941. Hitler (Bio Hitler) gambled on a quick victory so the Soviet Union would be defeated before the onset of the feared winter. "We only have to kick in the front door and the entire rotten edifice will collapse," as Hitler told Generalfeldmarschall Gerd von Rundstedt (Bio Von Rundstedt) about the Soviet Union. Many officers agreed with him. Rittmeister von Rosenbach-Lepinski, commander of the 24. Panzerdivision allegedly had said that the war against the Soviet Union would last just four weeks.
Because German forces were attacking the Balkans in the spring of 1941, the operation was postponed. Hitler had changed the name Fall Fritz to Operation Barbarossa after the Emperor of the Holy Roman Empire who had led the Third Crusade. Now, his name would be used for the crusade against Bolshevism. Hitler told his generals: "When Operation Barbarossa is launched, the world will hold its breath." At 03:15 in the morning of Sunday, June 22nd, 1941, Operation Barbarossa, the invasion of the Soviet Union, was unleashed. The largest military operation of all time had begun.
The invasion force consisted of three army groups (Heeresgruppe) numbering 3,050,000 men, 3,580 armored vehicles, 7,184 guns, 600,000 trucks, over 600,000 horses and 1,830 aircraft. Heeresgruppe Nord with 26 divisions was commanded by Generalfeldmarschall Wilhelm Ritter von Leeb (Bio Von Leeb), Heeresgruppe Mitte counting 47 divisions was commanded by Generalfeldmarschall Fedor von Bock (Bio Von Bock) and Heeresgruppe Süd, numbering 43 divisions, was commanded by Generalfeldmarschall Gerd von Rundstedt. Those were faced on Soviet side by three so called fronts; the Northwest Front, the West Front and the Southwest Front, totaling 158 divisions and 54 brigades. Joseph V. Stalin (Bio Stalin) was completely taken by surprise, as he had expected an invasion only when Great Britain had been captured.
Initially, the invasion proceeded successfully. 17 days into the attack, Heeresgruppe Mitte alone had taken 300,000 Soviet prisoners and had captured vast amounts of material. After 46 days, they had taken 850,000 prisoners. During the first days of the operation, the Luftwaffe destroyed 3,000 aircraft on the ground as well as in the air, almost half of the entire Soviet air force.
Generalleutnant Erich Marcks, chief of staff of 18. Armee had proposed a two pronged advance to Moscow and Kiev with Moscow as the main target. Hitler however thought Leningrad should be the main target. He continuously interfered in the conduct of the battle, something that did not do the German army any good. Yet, the operation progressed very successfully for the Germans. Towards the end of September they had surrounded Leningrad, Odessa and Sevastopol. In December, they had taken 3,5 million prisoners and killed 4 million Soviet soldiers. Optimistic German planners thought they would have reached a line from Archangelsk in the north to Astrakhan in the south at the onset of winter in 1941. Along with the diminishing chaos on Soviet side during the summer, resistance intensified. Generaloberst Franz Halder, chief of the General Staff of the army felt less and less at ease. "Everywhere, the Russians fight to the last man, "he noted in his diary."They capitulate very rarely." The Soviets possessed vast reserves though. Six months after the start of Operation Barbarossa, they had established 300 new divisions.