Final answer:
Operation Barbarossa was a significant German invasion of the Soviet Union in 1941, which initially had great success but ultimately faltered due to overstretched supply lines and harsh winter conditions.
Step-by-step explanation:
During World War II, several significant military operations were launched by both the Germans and the Soviets, with some of the most notable being the German Operation Barbarossa and the Soviet counteroffensive that led to the liberation of Eastern Europe.
Operation Barbarossa, initiated in June 1941, was a massive invasion by the German Army into Soviet territory aimed at quickly defeating the Soviet Union using blitzkrieg tactics. Despite early successes and massive territorial gains, the German forces could not maintain their momentum against the vastness of Russia, its scorched earth policy, and the harsh winter conditions.