Case Blue

Case Blue (Fall Blau), later renamed 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.

The operation was a continuation of the previous year's Operation Barbarossa intended to finally knock the Soviet Union out of the war, and involved a two-pronged attack against the rich oilfields 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 (Wehrmacht Heer) 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 German offensive saw spectacular gains with a rapid advance into the Caucasus capturing vast areas of land and several oil fields. However, the Red Army decisively defeated the Germans at Stalingrad, following Operations Uranus and Little Saturn. This defeat forced the Axis to retreat from the Caucasus in fear of becoming trapped. Only the city of Kursk and the Kuban region remained tentatively occupied by Axis troops.

Background
On 22 June 1941 the Germans began Operation Barbarossa with the intention of defeating the Soviets in a Blitzkrieg lasting only months. The offensive met with initial success and the Red Army suffered some major defeats, before the Germans were stopped at Moscow. Although the Germans captured vast areas of land and important industrial centers, the Soviet Union remained in the war. In the winter of 1941/1942 the Soviets struck back in a series of counteroffensives, repelling the German threat to Moscow, and making it clear the campaign against the Soviets would become a long battle of attrition. Despite these setbacks, Hitler wanted an offensive solution, for which he required the rich oil resources of the Caucasus. By February 1942, the Army High Command (OKH) had begun to develop plans for a follow-up campaign to the failed Barbarossa offensive with the Caucasus as its principal objective. On 5 April 1942, Hitler laid out the key elements of the plan now known as "Case Blue" (Fall Blau) in Führer Directive No. 41. The directive stated the main goals of the summer campaign on the Eastern Front - holding attacks for AG Centre, the capture of Leningrad and link up with Finland for AG North and the capture of the Caucasus Region for Army Group South.

The oilfields
The immense Caucasus 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, adjoining the Caspian, produced about 10 percent of all Soviet oil. South of the mountains lay the densely populated region of Transcaucasia, comprising Georgia, Azerbaijan and Armenia. This heavily industrialised area, which had a greater population density than New York State, contained some of the largest oilfields in the world. Baku, the capital of Azerbaijan, was one of the richest, producing 80 per cent 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 contained vast swaths of wheat, corn, sunflower seeds and sugar beets, all essential in the production of food.

These resources were of immense importance to Hitler and the German war effort. Of the three million tons of oil Germany consumed per year, 85 per cent 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 only 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.

Axis forces
The offensive was to be conducted across the southern Russian (Kuban) steppe utilizing the following Army Group units:
 * Army Group A, under Wilhelm List (Caucasus campaign)
 * First Panzer Army
 * Seventeenth Army
 * Third Romanian Army
 * Eleventh Army


 * Army Group B, under Maximilian von Weichs (Volga campaign)
 * Second Army
 * Fourth Panzer Army
 * Sixth Army
 * Second Hungarian Army
 * Fourth Romanian Army
 * Eighth Italian Army


 * Luftflotte 4, under Alexander Löhr
 * Fliegerkorps VIII
 * Fliegerkorps IV

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. Initially commanded by Löhr, on 20 July 1942, Wolfram Freiherr von Richthofen took command of Luftflotte 4.

The German plan involved a three-staged attack:
 * Blau I: Fourth Panzer Army, commanded by Hermann Hoth (transferred from Army Group North) 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.
 * Blau II: Sixth Army, commanded by Friedrich Paulus, would attack from Kharkiv and move in parallel with Fourth Panzer Army, to reach the Volga at Stalingrad (whose capture was not deemed necessary).
 * Blau III: 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.

Soviet forces
The Soviet army command (Stavka) 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 Kharkiv. The Soviets recovered maps from his aircraft detailing the exact German plans for Case Blue. The plans were handed over to Stavka, in Moscow.

Joseph Stalin, however, believed it to be a German ruse, remaining convinced that the primary German strategic goal in 1942 would be Moscow, in part due to Operation Kremlin (Fall Kreml), 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 frontline 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 reorganised 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.

With the German thrust expected in the north, Stavka planned several local offensives in the south to weaken the Germans. The most important of these was aimed at the city of Kharkiv and would be conducted mainly by the Southwestern Front under Semyon Timoshenko, supported by the Southern Front commanded by Rodion Malinovsky. The operation was scheduled for 12 May, just prior to a planned German offensive in the area, which would prove disastrous for the operation. The ensuing Second Battle of Kharkov ended in disaster and severely weakened the Soviets. At the same time, the Axis clearing of the Kerch Peninsula together with the Battle of Sevastopol, which lasted until July, weakened the Soviets further and allowed the Germans to supply Army Group A across the Kerch Peninsula through the Kuban.

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's confidence for the upcoming major offensive.

Close air support from the Luftwaffe also played an important role in this early success. It contained the Red Air Force, through air superiority operations, and interdiction through attacks on airfields and Soviet defence lines. At times the German air arm acted as a spearhead rather than a support force, ranging on ahead of the tanks and infantry to disrupt and destroy defensive positions. As many as 100 German aircraft were concentrated on a single Soviet division in the path of the spearhead during this phase. General Kazakov, the Bryansk Front's chief of staff, noted the strength and effectiveness of Axis aviation. Within 26 days, the Soviets lost 783 aircraft from the 2nd, 4th, 5th and 8th Air Armies, compared to a German total of 175.

By 5 July, forward elements of Fourth Panzer Army had reached the Don River near Voronezh and became embroiled in the battle to capture the city. Stalin and the Soviet command still expected the main German thrust in the north against Moscow, and believed the Germans would turn north after Voronezh to threaten the capital. As a result, the Soviets rushed reinforcements into the town, to hold it at all costs and counterattacked the Germans' northern flank in an effort to cut off the German spearheads. Pavel Rotmistrov's 5th Tank Army managed to achieve some minor successes when it began its attack on 6 July, but was forced back to its starting positions by 15 July, losing about half of its tanks in the process. Although the battle was a success, Hitler and von Bock, commander of Army Group South, argued over the next steps in the operation. The heated debate, and continuing Soviet counterattacks, which tied down Fourth Panzer Army until 13 July, caused Hitler to lose his temper and dismiss von Bock. As part of the second phase of the operation, on 9 July, Army Group South was split into Army Group A and B with Wilhelm List appointed as commander of Army Group A in place of von Bock.

Only two weeks into the operation, on 11 July, the Germans began to suffer logistics difficulties, which slowed down the tempo of the advance. The German Sixth Army was continually delayed by fuel shortages. Eight days later, on 20 July, shortages of fuel were still undermining operations, leaving many units unable to execute their orders. The 23rd Panzer Division and 24th Panzer Division both became stranded during the opening phase. Once again, as it had done during the Norwegian Campaign in April 1940, and Barbarossa in 1941, the Luftwaffe's Junkers Ju 52 transport fleet flew in supplies to keep the army going. The situation remained difficult with German troops forced to recover fuel from damaged or abandoned vehicles, and in some cases, leave behind tanks and vehicles with heavy fuel consumption to continue their advance. This undermined the strength of the units, which were forced to leave fighting vehicles behind. Nevertheless, the Luftwaffe flew in 200 tons of fuel per day to keep the army supplied. Despite this impressive performance in keeping the army mobile, Löhr was replaced by the more impetuous and offensive-minded von Richthofen.

Splitting of Army Group South
Believing that the main Russian 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:
 * reorganized Army Group South into two smaller Army Groups, A and B;
 * tasked Army Group A with advancing to the Caucasus and capturing the oil fields (Operation Edelweiß);
 * tasked Army Group B with the offensive towards the Volga and Stalingrad (Operation Fischreiher).

There is no evidence Hitler was opposed by, or received complaints from Franz Halder, the Chief of the General Staff, or anyone else, about the directive until August 1942. The new directive created enormous logistical difficulties with Hitler expecting both Army Groups to advance along different logistics routes. Logistics lines were already at breaking point with ammunition and fuel shortages most apparent, and it would be impossible to advance using the present conservative supply rates he demanded. The divergence of the two Army Groups would also open a dangerous gap between the armies, which could be exploited by the enemy. Moreover, no effective deployment of tactical resources was made in light of the task at hand. Inexplicably the Italian Alpine Corps, of the Italian Army in Russia, did not arrive in the Caucasus Mountains with Army Group A, instead remaining with Paulus' Sixth Army. Army Group A was therefore expected to operate in mountain terrain with only three mountain divisions and two infantry divisions unsuited to the task.

The splitting of Army Group South enabled the launching of Operation Edelweiss and Operation Fischreiher, the two main thrusts of the army groups. Both groups now had to strive for their goals simultaneously, instead of achieving them consecutively on a phased basis. The success of Sixth Army's initial advance was such that Hitler ordered Fourth Panzer Army south to assist First Panzer Army in forcing a crossing of the lower Don River.

Breaking into the Caucasus
With heavy air support from the Ju 87s of Sturzkampfgeschwader 77, List's Army Group A recaptured Rostov, the "gate to the Caucasus", on 23 July 1942 without much resistance. The Luftwaffe was in complete control of the skies in the early phase of the operation thus easing the task of the ground forces. With the Don River crossing secured and Sixth Army's advance flagging on the Volga front, Hitler sent Fourth Panzer Army back to the Volga line, reassigning it to Army Group B. In doing so, the Germans wasted enormous amounts of precious fuel transferring the units by air and land to the Volga front.

After crossing the Don River on 25 July, Army Group A fanned out on a 200 km broad front from the Sea of Azov to Zymlianskaya. The German Seventeenth Army, along with elements of the Eleventh Army and the support of the Romanian Third Army, now manoeuvred west towards the Black Sea's eastern coast, while First Panzer Army attacked southeast. While Seventeenth Army could only advance steadily, First Panzer Army roamed at will through the Soviet lines. On 29 July the Germans cut the last direct railroad between central Russia and the Caucasus region, causing considerable panic among the Soviet High Command and Stalin, which was illustrated by the passing of the famous Order No. 227 - "Not a step back!". Salsk was captured on 31 July and Stavropol on 5 August. Although the Army Group made rapid ground during its advance, by 3 August its vanguard comprised only light mobile forces with most of the tanks lagging behind due to lack of fuel and logistical breakdowns. Despite the best efforts of Kurt Pflugbeil's Fliegerkorps IV, which flew in supplies around the clock, the problem did not abate.

On 9 August, First Panzer Army reached Maikop at the foothills of the Caucasus range, having advanced more than 480 km in less than two weeks. The western oil fields near Maikop were seized in a commando operation on 8–9 August. Shortly afterwards Pyatigorsk was taken. On 12 August, Krasnodar was captured and German mountain troops hoisted the Nazi flag on the highest mountain of the Caucasus, Mount Elbrus.

The German advance had been highly successful, but long lines of supply hindered the continued advance. Of primary deficiency was a lack of petrol. As the Black Sea was not considered safe for transit, fuel had to be brought by rail through Rostov, or flown in. The armoured divisions were sometimes at a standstill for weeks. Even the petrol trucks were without supplies, and oil had to be brought up on camels. With the Soviets often retreating instead of fighting, the number of captured Soviet troops fell short of expectations — only 83,000 in all. At the same time, the focus of the German command shifted to the struggle at Stalingrad. The High Command began pulling some of Kleist's mobile forces to assist in the battle. In addition, Kleist was required to give up the whole of his flak corps and most of his Luftwaffe support, with only reconnaissance aircraft being left behind. At the same time, the Soviets brought in a bomber force of about 800 aircraft, a third of which were operational. Lacking aircover and flak units, the Soviet bombers were able to harass and slow the German advance. The quality of the Soviet resistance increased as well, with many of the forces used coming from local levies. To Kleist's point of view, they fought with greater determination for their home territory. The number of replacements and supplies the Soviets committed increased as well. Faced with these difficulties, the Axis advance slowed from 28 August onwards.

Battle for the oilfields
Meanwhile in the southeast, the Wehrmacht headed in the direction of Grozny and Baku, the other important petroleum centres. More installations and industrial centres fell into German hands, many intact or only slightly damaged during the Russian retreat from the area. In August–September the Taman Peninsula and a part of the Novorossisk naval base were taken. Thereafter, the Germans continued their advance toward Tuapse along the Black Sea coast. In the east, Elista was taken on 13 August. Further south, the German advance stalled north of Grozny, after taking the town of Mozdok on 25 August. German paratroopers assisted a raging insurgency in Chechnya, operating behind the Soviet lines. However, the mountain troops failed to secure the Black Sea ports, and the advance fell short of Grozny as logistical issues arose once more. The Soviets, determined to defend the oil fields there, dug in the 9th and 44th Armies of the North Transcaucasian Front along the rocky Terek River bank in front (north) of the city. The Luftwaffe was unable to support the German land forces that deep within enemy territory, allowing Soviet aviation to attack Axis-held bridges and logistics virtually unopposed. The Germans crossed the river on 2 September, but progress was extremely slow.



In an attempt to improve the logistics situation, Axis naval vessels transported 30,605 men, 13,254 horses, and 6,265 motor vehicles across the Black Sea to the Caucasus from Romanian ports, between 1–2 September. Thus reinforced, the Germans captured most of the Black Sea naval bases, but stalled at Novorossisk, where the Soviet 47th Army dug in and prepared for a long siege. Novorossisk fell on 10 September 1942, after a bitter four-day battle. This was List's final victory in the Caucasus, and an incomplete one – the Soviet 47th Army still held the heights south of the port, and several strategically important coastal roads. Several attempts to push out of Novorossisk were repulsed with heavy losses. The Axis also proved unable to overcome coastal plain defences between Novorossisk and Tuapse, and had only the strength to stabilise the line. Romanian Army losses were particularly high with the Romanian 3rd Mountain Division nearly wiped out by a Soviet counter-attack on 25–26 September.

Meanwhile, further east, the Axis enjoyed greater success. On 1 September, the Germans took http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=Russian+Federation,+Kalmykiya,+poselok+Khulkhuta&aq=0&sll=37.0625,-95.677068&sspn=38.826758,107.138672&ie=UTF8&hq=&hnear=poselok+Khulkhuta,+Yashkul%27skiy+rayon,+Kalmykiya,+Russian+Federation&ll=46.31611,46.370888&spn=0.066277,0.209255&z=13&iwloc=A (Хулхута́), halfway between Elista and Astrakhan. During August and September, German patrols harassed and interrupted the railway between Kizlyar, northeast of Grozny, and Astrakhan, marking the farthest advance of the German forces towards the Caspian Sea. In the south, the First Panzer Army's advance on Grozny stalled after meeting heavy resistance on the ground from Soviet forces supported by the 14th Air Army, which blunted their attacks. By late September and into early October, logistics breakdowns and heavy resistance meant the Axis were barely moving.

Local attacks still proved successful. On 26 or 28 October 1942, the 2nd Romanian Mountain Division and 13th Panzer Division took Nalchik, capital of Kabardino-Balkaria, then captured 10,000 Soviets in two days, before the Axis advance toward Grozny stalled again west of the city at the town of Vladikavkaz. On 5 November, Alagir was seized and the Alagir-Beslan-Malgobek line would then mark the farthest German advance in the south. By this time, the gap between Army Group A and B had dangerously exposed them to a counter strike. Only the German 16th Motorized Infantry Division remained inside the gap, defending the left flank of the First Panzer Army by securing the road towards Astrakhan.

In November, after several unsuccessful Soviet counterattacks, the Germans decided to remain on the defensive, waiting for the spring of 1943 to resume the offensive if the Stalingrad operations proved successful.

Luftwaffe offensive against the oil fields
In the first week of October 1942, Hitler came to recognise that the capture of the Caucasus oil fields was unlikely before the Russian Winter forced the German forces to take up winter positions. Unable to capture them, he was determined to deny them to the enemy and ordered the Oberkommando der Luftwaffe (OKL) to inflict as much damage as possible.

On 8 October, Hitler called for the air offensive to be carried out no later than 14 October, as he required air assets for a major effort at Stalingrad. As a result, on 10 October 1942, Luftflotte 4'sFliegerkorps IV was ordered to send every available bomber against the oilfields at Grozny. The air fleet was in poor shape by this time – Von Richthofen had begun Case Blue with 323 serviceable bombers out of a total of 480. He was now down to 232, of which only 129 were combat ready. Nevertheless, the force could still deliver damaging blows. Attacks on the refineries reminded von Richthofen of the attacks on Sevastopol several months earlier. Thick black smoke rose from the refineries to a height 5,500 m. On 12 October further raids caused even more destruction. It had been a strategic mistake not to have made greater efforts to hit the oil refineries at Grozny and Baku sooner as their destruction would have been a greater blow to the Soviets than the loss of Stalingrad, where most of the air fleet was deployed. On 19 November, the Soviet counter-offensive at Stalingrad compelled von Richthofen to once more withdraw his units north to the Volga and bring an end to the aerial offensive.

Much damage was done at Grozny, but the remaining oilfields were beyond the logistical reach of the German Army as well as the fighter aircraft of the Luftwaffe. Grozny was within range of German bombers from Fliegerkorps IV, based near the Terek river. But Grozny and the captured oilfields at Maykop produced only ten per cent of Soviet oil. The main fields at Baku were out of German fighter range. German bombers could have reached them, but it meant flying the most direct, thus most predictable route without protection. In August it may have been possible to carry out these operations owing to the weakness of Soviet air power in the region, but by October it had been considerably strengthened.

Clearing the Don Bend
On 23 July the main body of Army Group B started its advance toward the Don River. The Germans now met with increasing Soviet resistance from the newly formed Stalingrad Front, made up of the 62nd and 64th Soviet Armies. On 26 July, XIV Panzer Corps broke through the Soviet lines and reached the Don River. The recently formed First and Fourth Tank Armies conducted several counterattacks against Sixth Army's advance, threatening XIV Panzer Corps, but neither attack by the inexperienced troops proved successful. In the south, Fourth Panzer Army made better progress against the Soviet 51st Army. After Hoth's Panzers crossed the Don, they started to advance on Kotelnikovo, reaching the town by 2 August. Heavy Soviet resistance convinced Paulus that the Sixth Army was not strong enough to cross the Don by itself, so he waited for Fourth Panzer Army to fight its way north. On 4 August, the Germans were still 97 km from Stalingrad. By 10 August, the Red Army had largely been cleared from the western bank of the Don River but Soviet resistance continued in some areas, further delaying Army Group B's eastward offensive. Furthermore the Wehrmacht could not make appreciable headway towards Stalingrad because of heavy logistical problems caused by the poor state of Soviet roads, which created bottlenecks and shortages of both munitions and fuel. To ease the situation, the Luftwaffe sent an ad-hoc force of 300 Ju 52s, enabling the German Army to forge ahead. In some cases, bombers were diverted from combat operations to supply missions under the so-called Stalingrad Transport Region force.

The stubborn Soviet defence at the Don River forced the Germans to commit more and more troops to an increasingly vulnerable front, leaving little in the way of reserves to back up the Axis divisions on either flank. Consequently, the Soviets launched several counterattacks on Army Group B's northern flank between Stalingrad and Voronezh. Between 20–28 August, 63rd Army together with 21st Army counterattacked near Serafimovich, forcing Italian Eighth Army to fall back. At the same time, 1st Guards Army attacked near Novo-Grigoryevskaja, extending its bridgehead. These and several other bridgeheads across the Don River, opposed by Eighth Italian and Second Hungarian Armies, would cause major difficulties for the Germans in the future.

On 23 August, Sixth Army finally crossed the Don River, allowing Army Group B to establish a defensive line on one of its bends. The Sixth Army reached Stalingrad's northern suburbs later that day, beginning the Battle of Stalingrad. The Hungarian, Italian and Romanian armies deployed for this task were now 60 km from Stalingrad, which was also within reach of forward air bases. Consequently, bombers of Luftflotte 4 attacked the city, turning much of it to rubble. Soviet reports at the time asserted that civilian casualties between the 23–26 August, were 955 dead and 1,181 wounded. Although the final figures are likely to have been much higher than this preliminary total, reports of civilian casualties numbering tens of thousands were probably exaggerations by the Soviets.

The two-pronged ground attack on Stalingrad involved the Sixth Army advancing from the north (Kalach) and Fourth Panzer Army coming up from the south (Kotelnikovo). In the first few days, XIV Panzer Corps opened a narrow breach between the main Sixth Army's body and the northern Stalingrad suburbs at the Volga River while in the south, heavy Soviet resistance prevented Fourth Panzer Army from making any headway. On 29 August another attempt was made with Hoth turning his forces west directly through the center of the 64th Army. The attack brought unexpected success, and Hoth's men found themselves in the rear areas of both the 62nd and 64th Armies. This created a salient and opened the opportunity to encircle and cut off the 62nd Army. Hoth continued his drive and von Weichs ordered the Sixth Army to complete the encirclement, but a strong Soviet counterattack held up its advance for three vital days, enabling Soviet forces in the salient to escape and fall back towards Stalingrad.

Despite this close escape, the rapid German advance caused considerable morale breakdown among the Soviet troops, who retreated in chaos, abandoning the outer defences of the city. After neutralizing the last limited local Soviet counterattacks, the Sixth Army resumed its offensive on 2 September and linked up with Fourth Panzer Army the following day. On 12 September, the Germans entered Stalingrad itself and fighting within the city began the next day.

The Battle of Stalingrad
The advance into Stalingrad against the defenders of the 62nd Army was carried out by the worn out forces of the Sixth Army, while Fourth Panzer Army secured the southern flank. The city itself sprawled in a narrow, 24 km ribbon along the western side of the Volga River, which forced the Germans to conduct a frontal assault against the city, with the ruins of the city heavily favoring the defenders. To deal with the complete air superiority of the Luftwaffe, the commander of the 62nd Army, General Vasily Chuikov, ordered his troops to engage the Germans in close quarters fighting ('hugging' the enemy), rendering the German superiority in combined arms tactics almost useless. The Luftwaffe nevertheless played a crucial role, as it suppressed Soviet artillery on the eastern bank of the Volga and caused heavy casualties to the Soviet attempts to reinforce the defenders over the river. From mid September until early November, the Germans started three heavy assaults against the city, gradually but steadily reducing the perimeter the Soviets held more and more. Although Soviet casualties in the macabre street fighting were staggering, the German troops also took enormous losses. By mid November, the Soviet-held territory was reduced to just four shallow bridgeheads, with the front lines only 180 m from the river. Anticipating victory, substantial numbers of Luftwaffe aircraft were withdrawn to the Mediterranean in early November, to support the Axis operations in Tunisia. Although Sixth Army now held about 90% of the city, it was nevertheless unable to destroy the last pockets of resistance in time.

On 19 November, the Soviets launched Operation Uranus, a massive two-pronged counteroffensive against Sixth Army's flanks. With Sixth Army almost completely embroiled in the battle for the city and Fourth Panzer Army exhausted, these flanks were mainly guarded by Romanian, Hungarian, and Italian soldiers. Third Romanian Army, situated on the Don River west of Stalingrad, as well as Fourth Romanian Army to the Southeast of Stalingrad, had been under constant Soviet attack since September. Third Romanian Army had been transferred from the Caucasus on 10 September to take over the Italian positions on the Don and oppose the Soviet bridgeheads. The Romanians, who were in the direct path of the Soviet offensive, were therefore understrength and had only around six modern anti-tank guns per division. The bulk of the German tank reserve, the 48th Panzer Corps, consisted of roughly 180 tanks, of which half of them were obsolete Panzer 35(t)s. As a result, the two Romanian armies were routed, and the Sixth Army as well as parts of Fourth Panzer Army were trapped inside Stalingrad.

Hitler, against the advice of most of the involved army commanders, personally ordered Sixth Army to remain on the defensive rather than try to break out. It was intended the Army be re-supplied by air; since the required quantity of supplies was far beyond Luftwaffe delivery capabilities, the fighting strength of Sixth Army diminished and the Soviets gained the upper hand inside the city. To stabilise and restore the situation on the Eastern Front, Army Group Don (Heeresgruppe Don) under Field Marshal von Manstein was created to fill the gap between Army Group A and B. On 12 December, a relief operation called Operation Winter Storm began. Spearheaded by some of the first Tiger tanks, the offensive was able to drive within 48 km of the southern edge of the Sixth Army's front, although the trapped German forces made no attempt to link up with the relief forces. The failed relief efforts led to a siege that lasted for almost three additional months, during which the Sixth Army was ultimately destroyed.

Soviet counter strokes and aftermath


Following on from the success of Uranus, the Red Army began Operation Saturn, a plan designed to cut off the entire German Army Group A and all troops east of Rostov from the rest of the Heer. As a result of Manstein's relief operation at Stalingrad, Soviet forces had been redeployed, so the operation was now dubbed "Little Saturn" and its objectives scaled down. The operation targeted Eighth Italian Army and the remnants of Third Romanian Army and led to the destruction of most of the Italian forces. Although on the verge of collapse, Army Group B and Don were able to prevent a major Soviet breakthrough, but with Army Group A threatened with being cut off, it was ordered to withdraw from the Caucasus on 28 December.

In the following months the Soviets launched several follow-up offensives, summing up as the Voronezh-Kharkov Strategic Offensive. The Ostrogozhsk–Rossosh Offensive, launched on 12-13 January, destroyed large parts of the Second Hungarian Army and the remnants of Eighth Italian Army at the Don southeast of Voronezh. With its southern flank in danger, the German Second Army was forced to withdraw from Voronezh and the Don. Those successful operations from November until January led Stavka to believe that they could deal a fatal blow to the Germans to decide the war in southern Russia. Operation Star, conducted by the Voronezh Front, was aimed at Kharkiv, Kursk, and Belgorod, and Operation Gallop, conducted by the Southwestern Front, was aimed at Voroshilovgrad, Donetsk and then towards the Sea of Azov to cut off all German forces east of Donetsk. The operations were launched simultaneously at the end of January and the Soviets were able to break through the German lines during the first days. In the north Kursk fell on 8 February and Kharkiv on 16 February after a German withdrawal, while in the south the Germans were pushed back to a line west of Voroshilovgrad. Facing this increasingly precarious situation, Army Group Don, B and parts of Army Group A were reunited as Army Group South under Manstein's command on 12 February.

With the initial success of the Soviet offensives, the Kharkiv and Donbas operations were launched on 25 February. They were conducted by the newly formed Central Front led by Rokossovsky, which was made up from forces freed after the surrender of the German forces in Stalingrad on 2 February. The operations were aimed at Army Group Centre in the north and timed to coincide with the anticipated successes of the Soviet operations in the south. Despite those heavy blows, Manstein's forces, fighting a vigorous defense campaign, were not cut off and prepared for an own counteroffensive, which would lead to the Third Battle of Kharkov and the stabilisation of the front.

The disaster at Stalingrad marked the failure of Case Blue. Thereafter all previous gains had been reversed by the end of 1943, with the Kuban bridgehead, established at the Taman peninsula for a possible second thrust into the Caucasus, being the last to be evacuated on 9 October 1943.

Post-operation analysis
Due to the significant initial successes of the 1942 German summer offensive, the German command and especially Hitler expanded the already sophisticated plan even more, putting great strain on their forces. Hitler did not expect the Soviets to be able to launch a counteroffensive on the scale of Operation Uranus, and therefore deployed valuable units elsewhere on the front, while ordering the Wehrmacht to simultaneously strive for numerous goals. Any opposition to his fluctuating plans simply led to dismissal by Hitler, who interfered more and more in the command process.

Overstretched by the vast area they had captured, the reduced capabilities of the Heer and its allies to defend this territory enabled the Soviets to mount a decisive offensive at Stalingrad, encircling a whole German army. Soon both sides concentrated largely on the epic struggle for the city, making the Caucasus campaign a secondary theatre. With Army Group B unable to hold the Volga line, subsequent Soviet operations threatened to cut off Army Group A in the Caucasus, and it was forced to withdraw. The surrender of Sixth Army was a serious blow to German morale in general and it proved a personal shock to Hitler. Nevertheless, despite the destruction of Sixth Army, the Soviets only caused the Heer to retreat from their advance towards the Caucasus, further delaying the final decision on the Eastern Front. The by now highly confident Soviet command overestimated its capabilities and pushed its forces deep into the German lines, to the limit of its supply lines, which led to a severe defeat at Kharkov and gave the Germans the opportunity to mount another large strategic offensive.