Hitler breaks his own pact with the largest invasion in history
What happened
Under the codename Operation Barbarossa, Germany and its allies launched more than 3.5 million troops across a front stretching from the Baltic to the Black Sea, the largest military operation ever assembled, breaking the Nazi-Soviet Pact less than two years after signing it. German commanders had planned this invasion as a war of annihilation from the start: Einsatzgruppen, mobile killing squads, followed directly behind the advancing army to begin the mass shooting of Jews and Communist officials, and military planners expected, and accepted, that tens of millions of Soviet civilians would starve under German occupation policy. German forces reached the outskirts of Moscow by early December, their furthest advance, before a Soviet counteroffensive on 6 December drove them back in the first major German retreat of the war.
Why it matters
Barbarossa opened what became the deadliest theater of the entire war and the setting for most of the Holocaust's mass shootings, but the invasion's own success sowed its failure: German planners, expecting a quick Soviet collapse, had not equipped their troops for winter warfare, and the overextended front never fully recovered from its first winter.
How we know
German Army High Command directives and the RSHA's own coordination records for the Einsatzgruppen survive in the postwar documentary record, letting historians trace both the military campaign and the mass-killing operations that accompanied it from planning through execution.
Sources
- Holocaust Encyclopedia, US Holocaust Memorial Museum. Invasion of the Soviet Union, June 1941 · Reputable sourceencyclopedia.ushmm.org · The domain "encyclopedia.ushmm.org" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
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