Operation Barbarossa was the code name for the Axis invasion of the Soviet Union, the largest military operation in history. Over 3 million German and Axis troops invaded along a 1,800-mile front, breaking the non-aggression pact. Hitler's goal was the 'Lebensraum' (Living Space)—the conquest of Western Russia to destroy Communism and enslave the Slavic people for the benefit of the Aryan race. Initially, the Wehrmacht achieved massive victories, capturing hundreds of thousands of Soviet soldiers. However, the vast distances, the 'scorched earth' policy of the retreating Red Army, and the onset of the brutal Russian winter eventually stalled the German advance outside Moscow. The invasion opened the Eastern Front, where the vast majority of German casualties in World War II would occur in a war of annihilation.