German soldiers from 6. Armee Bivouac in an unknown Ukrainian village - waiting for the order to march - during Unternehmen Blau (Operation Blue), summer 1942. The picture was taken by Hans Eckle, a soldier from 587.Infanterie-Regiment / 320.Infanterie-Division. Unternehmen Blau or Fall Blau (Case Blue) was the German Armed Forces' name for its plan for the 1942 strategic summer offensive in southern Russia between 28 June and 24 November 1942. The operation was a continuation of the previous year's Operation Barbarossa, intended to knock the Soviet Union out of the war, and involved a two-pronged attack against the oil fields of Baku as well as an advance in the direction of Stalingrad along the Volga River, to cover the flanks of the advance towards Baku. For this part of the operation, Army Group South (Heeresgruppe Süd) of the German Army was divided into Army Groups A and B (Heeresgruppe A and B). Army Group A was tasked with crossing the Caucasus mountains to reach the Baku oil fields, while Army Group B protected its flanks along the Volga. Initially, the offensive saw gains, with an advance into the Caucasus capturing large areas of land and several oil fields. The possibility that the Germans would continue to the south and east, and possibly link up with Japanese forces (then advancing in Burma) in India, was of great concern to the Allies. However, the Red Army defeated the Germans at Stalingrad, following Operations Uranus and Little Saturn. This defeat forced the Axis to retreat from the Caucasus. Only the city of Kursk and the Kuban region remained tentatively occupied by Axis troops.