As the city devolved into a maelstrom of carnage, Zhukov began building up his forces on the city's flanks. On November 19, 1942, the Soviets launched Operation Uranus, which struck and broke through the weakened German flanks around Stalingrad. Advancing quickly, they encircled the German Sixth Army in four days. Trapped, the Sixth Army's commander, General Friedrich Paulus, requested permission to attempt a breakout but was refused by Hitler. In conjunction with Operation Uranus, the Soviets attacked Army Group Center near Moscow to prevent reinforcements being sent to Stalingrad. In mid-December, Field Marshall Erich von Manstein organized a relief force to aid the beleaguered Sixth Army, but it was unable to break through the Soviet lines. With no other choice, Paulus surrendered the remaining 91,000 men of the Sixth Army on February 2, 1943. In the fighting for Stalingrad, over 2 million were killed or wounded.
The invasion was a ghastly failure for the Russians, a setback which was followed by considerable German advances in the following year, including the capture of the Polish city of Warsaw . However, the crisis caused in the German High Command by the unexpected Russian advance forced the sending of 2 corps and a cavalry division from the Western Front as part of the new 9th Army in order to support the attack on the Russians. These additional forces did not arrive in time for the twin battles, as Ludendorff predicted and, had they entered France as originally planned could have been tremendously helpful to the precarious situation in the West. In the head of French Intelligence Colonel Dupont's words, "their debacle was one of the elements of our victory."