Case Blue (German: Fall Blau), later named Operation Braunschweig, was the German Armed Forces' (Wehrmacht) name for its plan for the 1942 strategic summer offensive in southern Russia between 28 June and 24 November 1942, during World War II.
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.
The Caucasus, a large, culturally diverse region traversed by its eponymous mountains, is bounded by the Black Sea to the west and the Caspian Sea to the east. The region north of the mountains was a production center for grain, cotton and heavy farm machinery, while its two main oilfields, at Maykop, near the Black Sea, and Grozny, about halfway between the Black and the Caspian Seas, produced about 10 percent of all Soviet oil. South of the mountains lay Transcaucasia, comprising Georgia, Azerbaijan and Armenia. This heavily industrialized and densely populated area contained some of the largest oilfields in the world. Baku, the capital of Azerbaijan, was one of the richest, producing 80 percent of the Soviet Union's oil—about 24 million tons in 1942 alone.
The Caucasus also possessed plentiful coal and peat, as well as nonferrous and rare metals. Manganese deposits at Chiaturi, in Transcaucasia, formed the richest single source in the world, yielding 1.5 million tons of manganese ore annually, half of the Soviet Union's total production. The Kuban region of the Caucasus also produced large amounts of wheat, corn, sunflower seeds, and sugar beets, all essential in the production of food.
see:Hayward, Joel (1995). Too Little Too Late: An Analysis of Hitler's Failure in 1942 to Damage Soviet Oil Production. Lawrence, KS: The Journal of Strategic Studies, Vol. 18, No. 4, pp. 94–135
