Case Blue
Axis forces
The strategic objectives of the operation were the oilfields at Maykop, Grozny and Baku. As in Barbarossa, these movements were expected to result in a series of grand encirclements of Soviet troops.
Opening phase
The German offensive commenced on 28 June 1942, with Fourth Panzer Army starting its drive towards Voronezh. Due to a chaotic Soviet retreat, the Germans were able to advance rapidly, restoring Wehrmacht confidence for the upcoming major offensive.
Splitting of Army Group South
Believing that the main Soviet threat had been eliminated, desperately short of oil and needing to meet all the ambitious objectives of Case Blue, Hitler made a series of changes to the plan in Führer Directive No. 45 on July 23, 1942: