Case Blue () was the Wehrmacht plan for the 1942 summer offensive in southern Russia between 28 June and 24 November 1942, during World War II. The objective was to capture the oil fields of Baku (Azerbaijan SSR), Grozny and Maikop, to enable the Germans to obtain fuel and also to deny it to the Soviet Union, bringing about the complete collapse of the Soviet war effort.
After Operation Barbarossa failed to destroy the Soviet Union as a political and military threat the previous year, Adolf Hitler recognized that Germany was now locked in a war of attrition and he was also aware that Germany had a chronic fuel shortage and would not be able to continue attacking deeper into Soviet territory without more. Hitler ordered the preparation of offensive plans for summer 1942 to secure the Soviet oil fields in the Caucasus. The operation involved a two-pronged attack: one from the Axis right flank against the oil fields of Baku, known as Operation Edelweiss, and one from the left flank to protect the flank of the first attack, moving in the direction of Stalingrad along the Don River, known as Operation Fischreiher..
Army Group South () was divided into Army Group A and Army Group B ( and ). Army Group A was to fulfil Operation Edelweiss by crossing the Caucasus Mountains to reach the Baku oil fields, while Army Group B protected its flanks along the Volga by fulfilling Operation Fischreiher. Supported by 2,035 Luftwaffe aircraft and 1,934 tanks and assault guns, the 1,570,287-man Army Group South began the offensive on 28 June, advancing 48 kilometers on the first day and easily brushing aside the 1,715,000 Red Army troops opposite, who wrongly expected a German offensive on Moscow even after commenced. The Soviet collapse in the south allowed the Germans to capture the western part of Voronezh on 6 July and reach and cross the Don River near Stalingrad on 26 July. Army Group B's approach toward Stalingrad slowed in late July and early August owing to constant counterattacks by new Red Army reserves and overstretched German supply lines. The Germans defeated the Soviets in the Battle of Kalach and the Battle of Stalingrad began in late August. Non-stop Luftwaffe bombing, artillery-fire and street fighting destroyed the city and inflicted many casualties on the Red Army. After three months of battle, the Germans controlled 90 percent of Stalingrad on 19 November.
In the south, Army Group A captured Rostov-on-Don on 23 July and swept south from the Don to the Caucasus, capturing the demolished oilfields at Maikop on 9 August and Elista on 13 August near the Caspian Sea coast. Determined Soviet resistance and the long distances from Axis sources of supply reduced the Axis offensive to local advances only and prevented the Germans from completing their strategic objective of capturing the main Caucasian oilfield at Baku. Luftwaffe bombers destroyed the oilfields at Grozny but attacks on Baku were prevented by the short range of the German fighters.
The Red Army defeated the Germans at Stalingrad, following Operation Uranus and Operation Little Saturn. This defeat forced the Axis to retreat from the Caucasus during the Battle of Caucasus to avoid being cut off by the Red Army, that was now advancing from Stalingrad towards Rostov. Only the Kuban region remained tentatively occupied by Axis troops.
Axis strategy
Background
On 22 June 1941, Germany launched Operation Barbarossa to defeat the Soviet Union in a Blitzkrieg which was expected to last only three months. The Axis offensive had met with initial success and the Red Army had suffered some of the greatest defeats in military history, before halting the Axis units just short of Moscow (November–December 1941). The Germans had captured vast areas of land and important industrial centers but the Soviet Union remained in the war. In the winter of 1941–1942, the Soviets struck back in several successful counter-offensives, pushing back the Germans from Moscow. Despite these setbacks, Hitler wanted the complete destruction of Russia, for which he required the oil resources of the Caucasus.
By February 1942 the German Army High Command (OKH) had begun to plan for a follow-up campaign to Barbarossa – with the Caucasus as its principal objective. On 5 April 1942, Hitler laid out the elements of the plan, now "Case Blue" () in Führer Directive No. 41. The directive outlined the main goals of the 1942 summer campaign on the Eastern Front, holding attacks for Army Group Centre, the capture of Leningrad and the link-up with Finland for Army Group North and the capture of the Caucasus for Army Group South. The (main effort) was to be in the south.
The oilfields 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 largest oilfields, at Maikop, 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 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 oil—about 24 million tons in 1942..
The Caucasus also possessed plentiful coal, peat, nonferrous and rare metals. Manganese deposits at Chiatura, 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.
These resources were of immense importance to the German war effort. Of the three million tons of oil Germany consumed per year, 85 percent was imported, mainly from the United States, Venezuela, and Iran. When war broke out in September 1939, the British naval blockade cut Germany off from the Americas and the Middle East, leaving the country reliant on oil-rich European countries such as Romania to supply the resource. An indication of German reliance on Romania is evident from its oil consumption; in 1938, just one-third of the 7,500,000 tons consumed by Germany came from domestic stocks. Oil had always been Germany's Achilles heel, and by the end of 1941, Hitler had nearly exhausted Germany's reserves, which left him with only two significant sources of oil, the country's own synthetic production and the Romanian oilfields, with the latter supplying 75% of Germany's oil imports in 1941. Aware of his declining oil resources, and fearful of enemy air attacks on Romania (Germany's main source of crude oil), Hitler's strategy was increasingly driven by the need to protect Romania and acquire new resources, essential if he wanted to continue waging a prolonged war against a growing list of enemies. In late 1941, the Romanians warned Hitler that their stocks were exhausted and they were unable to meet German demands. For these reasons, the Soviet oilfields were extremely important to Germany's industry and armed forces as the war became global, the power of the Allies grew, and shortages started to occur in Axis resources.
Planning
Axis forces
The German plan involved a three-staged attack: : Fourth Panzer Army, commanded by Hermann Hoth (transferred from Army Group Centre) and the Second Army, supported by the Second Hungarian Army, would attack from Kursk to Voronezh and continue the advance, anchoring the northern flank of the offensive towards the Volga. : Sixth Army, commanded by Friedrich Paulus, would attack from Kharkov and move in parallel with Fourth Panzer Army, to reach the Volga at Stalingrad (whose capture was not deemed necessary). : First Panzer Army would then strike south towards the lower Don River, with Seventeenth Army on the western flank and Fourth Romanian Army on the eastern flank.
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..
The offensive was to be conducted across the southern Russian (Kuban) steppe utilizing the following Army Group units:.
Northern Sector (Volga campaign) Army Group B Generaloberst Maximilian von Weichs Second Army (General Hans von Salmuth) LV Army Corps (R. von Roman) Fourth Panzer Army (Generaloberst Hermann Hoth) XXIV Panzer Corps (W. Langermann und Erlenkamp) XXXXVIII Panzer Corps (W. Kempf) XIII Army Corps (E. Straube) Sixth Army (General der Panzertruppe Friedrich Paulus) XXXX Panzer Corps (G. Stumme) LI Army Corps (W. von Seydlitz-Kurzbach) VIII Army Corps (W. Heitz) XVII Army Corps (K. Hollidt) XXIX Army Corps (H. von Obstfelder) Hungarian Second Army (Colonel-General Vitéz Gusztáv Jány) III Corps (G. Rakovsky) VII Army Corps (Wehrmacht) (E.-E. Hell) Arrived 21–25 July: IV Corps (L. Csatay) VII Corps (E. Gyimesi) Romanian Fourth Army
Italian Eighth Army (Arrived 11–15 August) (General Italo Gariboldi) II Corps (G. Zanghieri) XXXV Corps (G. Messe) Alpini Corps (G. Nasci) Luftflotte 4 Generaloberst Alexander Löhr (thru 20 July) Generalfeldmarschall Wolfram Freiherr von Richthofen (from 20 July) 8th Air Corps 4th Air Corps German air strength in the east numbered 2,644 aircraft on 20 June 1942, over 20% more than a month earlier. Whereas in 1941 most units fought on the central front supporting Army Group Centre, 1,610 aircraft (61%), supported Army Group South..
Southern Sector (Caucasus campaign) Army Group A Generalfeldmarschall Wilhelm List First Panzer Army Seventeenth Army Third Romanian Army Eleventh Army
Soviet forces The Soviet army command () failed to discern the direction of the main German strategic offensive anticipated in 1942, even though they were in possession of the German plans. On 19 June, the chief of operations of the 23rd Panzer Division, Major Joachim Reichel, was shot down over Soviet-held territory while flying an observation aircraft over the front near Kharkov. The Soviets recovered maps from his aircraft detailing the exact German plans for Case Blue. The plans were handed over to , in Moscow.
Joseph Stalin, however, believing it to be a German ruse, remained convinced that the primary German strategic goal in 1942 would be Moscow, in part due to Operation Kremlin (), a German deception plan aimed at the city. As a result, the majority of Red Army troops were deployed there, although the direction from which the Case Blue offensive would come was still defended by the Bryansk, Southwestern, Southern and North Caucasian Fronts. With about 1 million soldiers at the front line and another 1.7 million in reserve armies, their forces accounted for about one quarter of all Soviet troops.. Following the disastrous start of Case Blue for the Soviets, they reorganized their frontlines several times. Over the course of the campaign, the Soviets also fielded the Voronezh Front, Don Front, Stalingrad Front, Transcaucasian Front, and the Caucasian Front, though not all existed at the same time.