Operation Barbarossa was the code name for Nazi Germany's invasion of the Soviet Union, which began on June 22, 1941.

It was the largest land invasion in the history of warfare, involving millions of soldiers along an 1,800-mile front.

Hitler's motivations were both ideological (to destroy communism) and strategic (to acquire 'Lebensraum' or living space for Germany).

The invasion was a direct violation of the Nazi-Soviet Non-Aggression Pact of 1939.

In the initial phase, the German Blitzkrieg was highly successful, leading to the capture of vast territories and millions of Soviet soldiers.

The war on the Eastern Front was exceptionally brutal, characterized by Nazi racial extermination policies.

The German advance was halted in the winter of 1941 by the harsh Russian weather and stiffening Soviet resistance at the gates of Moscow.

The Siege of Leningrad lasted for nearly 900 days and resulted in the deaths of over a million civilians from starvation.

The Battle of Stalingrad is considered the decisive turning point of the war on the Eastern Front.

The failure of Operation Barbarossa opened up a massive war of attrition that Germany ultimately could not win.