22 June 1941. Nearly four million German and allied troops cross the Soviet border on a front from the Baltic to the Black Sea, the largest invasion in history. Stalin has spent years shooting his own officers. Whole armies are encircled; by December the Red Army has lost more than four million men.
Why then
Hitler wants living space, Ukrainian grain and Caucasus oil, and has told his generals this will be a war of annihilation. The pact with Stalin was a pause. Stalin had months of warnings from his own spies and refused to believe them.
What they wanted
Berlin expects the Soviet state to collapse before winter, and its planners count on millions of Soviet civilians starving so the army and the Reich can eat. Moscow gives ground to buy time and moves whole factories east of the Urals.
What changed
Behind the front, SS killing squads shoot Jews by the hundreds of thousands: the Holocaust in the east has begun. Leningrad is encircled in September; some 800,000 of its people will starve in a siege of almost 900 days. The rain comes, then the cold, and Moscow holds in December.
Still argued
Was the invasion lost in the distances from the start, or did the Soviet recovery of 1941 have to be earned? Few historians now doubt that mass murder was planned in from the beginning.