On December 18, 1940, Hitler issued “Directive No. 21 Operation Barbarossa,” whereby the Wehrmacht leadership was ordered to prepare for an attack on the Soviet Union the following year. The operations plan foresaw a spectacular blitzkrieg offensive in which three army groups (North, Center, and South) would rapidly defeat the Red Army by driving wedges into Soviet troops and surrounding them. According to plan, the Wehrmacht would then advance deep into the country's interior. The ultimate goal was to conquer the whole European part of the Soviet Union and secure a 1,860-mile front from Archangel to the Caspian Sea.