By early 1942, Adolf Hitler’s dream of destroying the Soviet Union seemed closer to fulfillment. Jackbooted German soldiers had marched victoriously through the streets of the communist nation’s major cities while their comrades laid siege to Leningrad and threatened the capital of Moscow. Then, late that summer, the Nazi leader attacked Stalingrad. That decision led to Germany’s first major Eastern Front defeat and became the turning point of World War II.

“If you look at the whole operation, the Soviets essentially wiped out the German Sixth Army and a Panzer army…leaving a massive hole in the Eastern Front,” says Stalingrad historian David Glantz, author of five books on the battle. “The Germans never fully recovered from it.”

With nearly 4 million combatants, the Battle of Stalingrad—fought August 23, 1942-February 2, 1943—dwarfed battles on the Western Front. The Nazis and their Hungarian, Romanian and Italian allies suffered more than one million casualties. More Red Army soldiers (nearly 480,000) died in the five-month defense of Stalingrad than Americans (416,800) in the entire war.

For Soviet citizens, the Red Army’s ferocious defense of Stalingrad—named for Hitler’s archenemy Joseph Stalin, the country’s leader—became a source of enormous national pride. Even German soldiers acknowledged the Soviets’ ability to withstand massive losses and endure fighting in brutal winter conditions in the city’s defense.

“The dogs fight like lions,” Nazi soldiers often said.

“Everyone in Stalingrad who still possesses a head and hands, women as well as men, carries on fighting,” a German corporal wrote to his father in October 1942.

Hitler’s campaign in the southern Soviet Union began as a major offensive into the Caucasus to secure oil for the Nazi war machine. Against the advice of senior commanders, who urged the mercurial leader to focus on one target, Hitler diverted Army Group South’s Sixth Army under General Friedrich Paulus to Stalingrad, a major industrial, communications and transportation hub along the Volga River.

After the Luftwaffe pummeled the city from the air, the Sixth Army nearly pushed the entire Red Army to the Volga’s east bank. But the Germans soon became bogged down in brutal, urban warfare amidst the city’s rubble.

“Stalingrad is no longer a city,” wrote a German soldier. “By day it is a cloud of burning, blinding smoke. When night arrives, the dogs plunge into the Volga and swim desperately to the other bank. Animals flee this hell; the hardest stones cannot bear it for long; only men endure.”

The Soviets, meanwhile, relished bleeding the Sixth Army dry: “[I]f we had not had any weapons, we would still have killed the people who had come to take our Volga from us with our bare hands,” a Red Army sergeant said.

On November 19, 1942, the Soviets launched “Operation Uranus,” a counteroffensive to encircle the already beleaguered Sixth Army and its allies. Three days later, the ring snapped shut, trapping 250,000 soldiers within an area roughly 30 miles wide by 20 miles deep.

Unable to get adequate supplies from the air from the Luftwaffe, the Sixth Army withered under incessant attacks. The temperature dipped so low that machines became inoperable. Thousands of Axis soldiers suffered from frostbite and malnutrition. Paulus requested permission to break out from the Kessel—the German word for cauldron—but Hitler refused. A German army rescue effort from outside the encirclement failed.

In late January 1942, Paulus appealed to Hitler for permission to surrender rather than risk annihilation. “Sixth Army will hold their position to the last man and the last round,” the Nazi leader replied, “and by their heroic endurance will make an unforgettable contribution toward the establishment of a defensive front and the salvation of the Western World.”

On January 31, 1943, Paulus left behind the waist-high excrement in his battered headquarters in the heart of Stalingrad and surrendered to the Soviets. When Hitler heard news, the often-volatile Führer stared silently into his soup.

The German public was not officially told of the catastrophic defeat until the end of January 1943. Hitler was so rocked by the disaster that on the 10th anniversary of the Nazis’ assumption of power in Germany on January 30, he didn’t deliver his usual radio speech. Propaganda minister Joseph Goebbels gave the speech instead.

Besides the mind-numbing human toll of Stalingrad, the Germans lost 900 aircraft, 500 tanks and 6,000 artillery pieces. With Soviet factories outproducing the Germans, the losses were impossible for the Nazis to make up.

As the tide turned, the Soviets benefited from Lend-Lease aid from America. “If the United States had not helped us, we would not have won the war," wrote future Soviet leader Nikita Khrushchev, who aided in the defense of Stalingrad (Volgograd today). "One-on-one against Hitler's Germany, we would not have withstood its onslaught and would have lost the war.”

At the Battle of Kursk in July 1943, the Soviets suffered at least 800,000 casualties to the Germans’ 200,000. But the Red Army’s costly victory put the Nazis on the defensive for the remainder of the war.

Meanwhile, in North Africa in late 1942, combined British, American and French forces also took the offensive against the Nazis. The Allies’ June 1944 invasion at Normandy pushed the Germans from France and eventually from Western Europe.

On November 9, 1944, with the Soviets on the doorstep of the Reich in Eastern Europe, Hitler blamed Stalingrad for Nazi’s Germany's impending demise.

As the Red Army marched across Eastern Europe, Soviet soldiers vowed to lay waste to Berlin as the Germans had Stalingrad.

By May 1945, they had.