The German invasion of Soviet Russia in June

1941 was the greatest military operation in history.

The 3.5 million-strong invasion force consisted

of three main army groups: Army Group North

attacked from East Prussia and fought along the

Baltic coastal lands towards Leningrad; Army

Group Centre moved towards Minsk, Smolensk,

and Moscow; and Army Group South advanced

towards Ukraine. In their invasion of the Soviet

Union, German forces used the same Blitzkrieg

tactics they had employed in 1939–1940 against

Poland, France, and the Low Countries. The codename for the German invasion

was Operation Barbarossa in honor of Frederick

I, the Holy Roman Emperor who organized a

12th century crusade to liberate the holy places of

Christianity from the Muslim control. According

to Nazi propaganda, the German campaign in

Russia was of a similar character—a crusade against

a Bolshevik regime that threatened European

civilization (Roberts, 2002:18).