Case Blue
Army Group South was selected for a sprint forward through the southern Russian steppes into the Caucasus to capture the vital Soviet oil fields there. The planned summer offensive, code-named "Fall Blau" (Case Blue), was to include the German 6th, 17th, 4th Panzer and 1st Panzer Armies. Army Group South had overrun the Ukrainian Soviet Socialist Republic in 1941. Poised in Eastern Ukraine, it was to spearhead the offensive.