By 1941, Nazi Germany seemed unstoppable. But beneath the surface, cracks were already forming—cracks that would widen into catastrophe.

In June 1941, Hitler launched Operation Barbarossa, the invasion of the Soviet Union. Confident of a rapid victory, he boasted: “We have only to kick in the door, and the whole rotten structure will come crashing down.” German forces raced deep into Soviet territory, encircling and destroying entire armies.

But Hitler was wrong.

By December 1941, the Wehrmacht had been halted at the very gates of Moscow and then thrown back by a fierce Soviet counteroffensive in brutal winter conditions. German troops, ill-equipped for the cold and stretched over vast distances, found themselves in a fight very different from what they had imagined.

At the same time, Germany’s strategic situation took a dramatic turn for the worse. Before Barbarossa, Germany had relied heavily on the Soviet Union for raw materials, including grain, oil, and metals. Once at war with their former partner, those supplies dried up. Worse still, in December 1941 the United States entered the war on the side of the Allies after Pearl Harbor. Now Hitler faced the nightmare he had always feared: a prolonged war on two fronts, against the industrial might of America and the vast manpower of the Soviet Union.

To have any chance of winning, Hitler believed he needed to defeat the USSR quickly and secure resources—especially oil. Germany’s own oil production and Romanian imports were nowhere near enough. For Hitler, the oilfields of the southern Caucasus—Maikop, Grozny, and eventually Baku—were the key. Without them, he saw no path to victory.

This led to Operation Blau (Case Blue) in 1942, the great German summer offensive in the east. But the plan that was supposed to deliver victory instead culminated in disaster at Stalingrad—the bloodiest battle of the Second World War.

To understand why, we have to go back to the beginning of that plan.

The German army that invaded the Soviet Union in 1941 was the largest offensive force ever assembled up to that point. But one year later, it was overstretched along a front of more than 2,500 kilometers. Army Group North was besieging Leningrad. Army Group Centre was embroiled in grinding battles around Rzhev. That left Army Group South to carry out Hitler’s next “decisive” blow with limited resources: 72 German divisions, about one million men.

Operation Blau was to unfold in phases. First, Axis forces would break through Soviet lines, capture Voronezh, and encircle Red Army units in eastern Ukraine. Once those formations were destroyed, Army Group South would split. Army Group B would move northeast to establish a defensive line along the Don and Volga, from roughly Voronezh toward Astrakhan. Army Group A would push south to seize the Caucasus oilfields.

If successful, Germany would gain access to vast food and fuel supplies while denying them to the Soviets. Hitler believed this would cripple the Soviet war machine and give Germany the means to continue fighting the Western Allies, including the United States.

The plan looked promising on paper, but it contained serious flaws in practice.

German logistics in the east were already strained to breaking point. The distances were huge, the rail system inadequate, and supply lines fragile. Germany also lacked sufficient forces for such ambitious objectives and had to rely heavily on allied troops—Romanian, Italian, Hungarian—who were often poorly equipped, especially in anti-tank weapons, and lacked German-quality artillery such as the feared 88mm gun.

Most critically, Hitler again underestimated Soviet strength. The Red Army could field more troops than the Germans and was forming new tank and air armies at an impressive rate. Blau was a high-risk gamble.

The offensive began on June 28th, 1942. Expecting stubborn resistance, the Germans instead found the Soviets in the south relatively weak. Stalin, anticipating another drive on Moscow, had concentrated resources further north. When the Germans attacked, many Red Army units in the south collapsed or fled. Within just over a week, Voronezh fell. It seemed Soviet forces in the south were finished.

Phase two of Blau began on July 9th, ahead of schedule. German forces moved toward Rostov and the great bend of the Don River, hoping to encircle and destroy retreating Soviet troops. But the Soviets continued to pull back. The German pincers closed on mostly empty space.

Meanwhile, in Germany, Hitler grew increasingly worried about the possibility of a second front in Western Europe. Allied raids—like the upcoming Dieppe raid in August 1942—weighed on his mind. Yet as he watched Soviet forces retreat, he became convinced that the way to secure victory lay in pushing harder, not pausing.

On July 23rd, 1942, Hitler changed the plan. Instead of focusing first on destroying Soviet forces and then turning to the Caucasus and the Volga, he ordered a simultaneous advance on both targets. Army Group A was to drive into the Caucasus. Army Group B, now led in part by Friedrich Paulus’s Sixth Army, was to head toward the Volga and capture the city of Stalingrad to cut Soviet oil traffic traveling north by river.

He also weakened Army Group South by sending some units to other fronts, confident that Soviet resistance was collapsing.

The change made a risky plan even worse.

German troops were already struggling with food and supply shortages. Frontline units were expected to “live off the land,” but scorched-earth tactics and devastated rural areas meant there was little to take. Ruthless requisitioning from local populations could not make up the shortfall. Sixth Army was killing and eating its horses well before it reached Stalingrad.

Army Group A initially made fast progress against scattered Soviet resistance and reached the Maikop oilfields by August 10th. But Soviet engineers had thoroughly sabotaged the wells and facilities. Restoring production would take time Germany did not have.

While Army Group A pushed south, Army Group B and Sixth Army were slowed by growing logistical problems and stiffening Soviet resistance. Soviet forces now fought delaying actions, taking heavy casualties but forcing the Germans to expend energy, fuel, and time. Hitler diverted units from the Caucasus to Paulus in an attempt to keep the advance going. Only with these reinforcements could Sixth Army resume its push.

After crossing the Don on August 23rd, Paulus’s men reached the northern outskirts of Stalingrad. The fight for the city was about to begin.

Stalingrad’s defense fell largely to the Soviet 62nd Army under General Vasily Chuikov. Chuikov, who had suffered humiliation in the Winter War against Finland, was determined not to fail again. Stalingrad also carried immense symbolic weight. It bore Stalin’s name. The Soviet leader poured in reserves and equipment to hold it at any cost. Large numbers of civilians remained too, sharing the fate of the soldiers as the city became a battlefield.

The battle began with a devastating German bombardment that turned much of Stalingrad into rubble. Thousands of civilians died. But the attack failed to break the city’s defenses. The ruins created a nightmare landscape ideal for defense and precarious for attackers. Buildings collapsed into jagged shells. Streets became corridors of fire.

The Germans, who had excelled at open-country maneuver—Blitzkrieg—now encountered large-scale urban warfare for the first time. In the city’s ruins, Soviet forces had the advantage. Red Army snipers became infamous, not only for the men they killed but for the terror and caution they induced among German troops forced to move from cover to cover.

By late September, Stalingrad had devolved into a deadly stalemate and propaganda symbol. Hitler became obsessed with capturing the city; Stalin was equally determined to hold it. Both leaders poured in more men and material. German casualties mounted. Soviet casualties were even greater, but replacements kept coming across the Volga.

Outside Stalingrad, the Soviets launched constant counterattacks along the flanks. These failed to break through, but they forced the Germans to commit reserves and stretched their lines even thinner. Further south, Army Group A was also encountering heavier resistance and struggling with its own supply problems, especially as air support shifted to the Stalingrad front.

The logistical situation for Army Group South was catastrophic. Only three single-track rail lines led to Stalingrad, and not all had been fully converted to German track gauge. Trains piled up, waiting to unload. Sixth Army was short of ammunition, fuel, food, and spare parts. Paulus barely had enough to sustain the units inside the city, let alone mount fresh attacks.

On the Soviet side, Chuikov’s 62nd Army, despite horrendous losses, continued to receive men, ammunition, and supplies ferried across the Volga. That lifeline, though fragile and under constant attack, stayed open.

German tanks were outnumbered and increasingly outclassed by the T-34. The T-34’s sloped armor, wide tracks, and robust design made it well suited to the Eastern Front. For years, German armored experts had acknowledged it as a formidable—and in many ways superior—design.

As autumn turned to winter, both Army Groups A and B were losing momentum. The Luftwaffe resorted to bombing oil facilities at Grozny rather than capturing them intact. In Stalingrad, Sixth Army was worn down, its combat units fighting on exhaustion and dwindling supplies. Still, by mid-November, Paulus controlled roughly 90% of the city. Soviet troops clung to narrow slivers of land along the Volga and pockets amidst the ruins.

Letters, diaries, and mementos from men like Fritz Lüderitz, a German soldier in the city, show how they tried to hold onto hope and normalcy—celebrating Christmas, writing to loved ones, even arranging proxy marriages under shell-shattered vaults—knowing many would never leave Stalingrad alive. Lüderitz himself was later reported missing, presumed dead.

By this time, Operation Blau—the grand plan for oil and victory—had effectively failed. The Caucasus oilfields were either wrecked or still controlled by the Soviets. German logistics were overwhelmed. The front was overstretched across more than 4,000 kilometers. The Red Army, which Hitler had insisted was on the verge of collapse, remained very much in the fight. In fact, it had been rebuilding and was now ready to strike.

On November 19th and 20th, 1942, the Soviets launched Operation Uranus. Two massive pincer offensives struck north and south of Stalingrad. Over a million men, 800 tanks, and 1,500 aircraft smashed into the Romanian and other Axis allied forces guarding the German flanks. Those troops—brave but poorly equipped and no match for Soviet armor—were quickly overwhelmed. Soviet tank formations surged into the gaps and raced westward behind the German lines.

German reserves were too weak and too few to stop them. On November 23rd, just days after Uranus began, the two Soviet pincers met near Kalach, west of Stalingrad. Sixth Army was encircled.

Hitler’s gamble had become a disaster.

From his headquarters, Hitler sent defiant messages to the trapped troops: “In these difficult hours my thoughts and those of the entire German people are with you… Everything that lies in my power will be done to support you in your heroic struggle.” In reality, there was very little he could do.

Many German commanders, including Manstein, urged that Sixth Army break out while it still had fuel and strength. Hitler refused. He would not abandon the city that now had such propaganda significance. Instead, he ordered the isolated army to hold fast while the Luftwaffe conducted an airlift and a relief force was assembled.

But the airlift was doomed from the start. It lacked enough transport aircraft, especially after losses in previous campaigns and against Allied air power. Weather, Soviet fighters, and poor airfield conditions made matters worse. Sixth Army needed roughly 600 tons of supplies per day. The Luftwaffe delivered only a fraction of that.

Manstein’s relief attempt, Operation Winter Storm, made some progress but stalled under Soviet pressure—especially after the Red Army launched Operation Little Saturn, a second offensive that smashed through Italian lines and threatened deeper rear areas. To avoid complete collapse in the south, Army Group A withdrew from the Caucasus. Sixth Army, now fully encircled, was left on its own.

By late January 1943, the remnants of Sixth Army were starving, freezing, and consumed by disease. Combat capability evaporated. On January 31st and February 2nd, the last pockets of resistance in Stalingrad surrendered. In a final twist of irony, Hitler promoted Paulus to Field Marshal shortly before the surrender, implicitly expecting him to commit suicide rather than be captured. Paulus chose to live.

The cost of Stalingrad was staggering. Between August 1942 and February 1943, roughly half a million Axis soldiers were killed, wounded, or taken prisoner in and around the city. More than 200,000 German and allied POWs fell into Soviet hands; only a small fraction, including Paulus, ever returned. Soviet casualties were even higher—well over a million killed, wounded, or missing. About half of that number were deaths. Soviet security troops also shot around 14,000 of their own soldiers for “cowardice” or “un-Soviet behavior.” An estimated 40,000 to 45,000 civilians died in the city.

Stalingrad was, in sheer numbers, the bloodiest battle of the war.

Its impact on the war was profound. It marked the high-water mark of Hitler’s ambitions in the east. From then on, the Wehrmacht would be on the defensive. It also marked the emergence of the Soviet Union as a major military power, positioned not only to survive but to push westward and eventually dominate Eastern Europe. At home, Hitler’s image as a brilliant military genius was badly damaged. Even Joseph Goebbels’ propaganda machine could not fully hide the scale of the disaster. Stalingrad was a key step on the path that would eventually lead German officers to plot against Hitler himself in July 1944.

In truth, the odds were stacked against Germany before Operation Blau and Stalingrad ever began. The plan was wildly ambitious and attempting it with insufficient forces and overstretched logistics was reckless. The Soviets, despite enormous losses, were rebuilding and learning. They took advantage of German overreach with skill and determination.

Stalingrad was one more in a series of high-stakes gambles that had defined Hitler’s war. In the early years—Poland, France, even the first phase of Barbarossa—those gambles had paid off. By 1942–43, they were failing catastrophically.

At the same time as Stalingrad, Axis forces were also suffering defeat at El Alamein in North Africa and facing Allied landings in French North Africa. These setbacks presaged the loss of Italy as an ally and opened a new front in the Mediterranean.

After Stalingrad, Germany’s war became a defensive struggle—one that grew more desperate with each passing month, and whose outcome, increasingly, had only one possible end.