What was the code name for Nazi-Germany's invasion of the Soviet Union that began on 22 June 1941?

Explanation

Operation Barbarossa (Unternehmen Barbarossa) was the code name for Nazi-Germany's invasion of the Soviet Union during World War II. The invasion started on 22 June 1941 when over 4.5 million troops of the Axis powers invaded the USSR. The operation was named after emperor Frederick Barbarossa from the Holy Roman Empire who led the third crusade in the 12th century. The Red Army had repelled the Wehrmacht's strongest blows in December 1941.