Operation Barbarossa's failure led to Adolf Hitler's demands for further operations inside the USSR, all of which eventually failed, such as continuing the Siege of Leningrad, Operation Nordlicht, and Battle of Stalingrad, among other battles on the occupied Soviet territory. Barbarossa was the largest military operation in human history in both manpower and casualties. Its failure was a turning point in the Third Reich's fortunes. Most important, Operation Barbarossa opened up the Eastern Front, to which more forces were committed than in any other theatre of war in world history.