Barbarossa, the invasion of Russia, 1941.  By Wayne Vansant

Knights of the Skull is a full-colour, graphic non-fiction series chronicling the development of the German Panzer (armoured) forces in World War II. Volume 2 starts with the April 1941 Balkans and Greece campaigns, then moves into the planning and early months of Operation Barbarossan the German invasion of the Soviet Union in June 1941