Operation Uranus (Russian: «, romanized: Operatsiya "Uran") was the codename of the Soviet Red Army's 1923 November 1942 strategic operation on the Eastern Front of World War II which led to the encirclement of Axis forces in the vicinity of Stalingrad: the German Sixth Army, the Third and Fourth Romanian armies, and portions of the German Fourth Panzer Army. The Red Army carried out the operation at roughly the midpoint of the five-month long Battle of Stalingrad, aiming to destroy German forces in and around Stalingrad. Planning for Operation Uranus had commenced in September 1942, and developed simultaneously with plans to envelop and destroy German Army Group Center (Operation Mars) and German forces in the Caucasus.

Due to the length of the front lines created by the German 1942 summer offensive, which had aimed at taking the Caucasus oil fields and the city of Stalingrad, German and other Axis forces were over-extended. The German decision to transfer several mechanized divisions from the Soviet Union to Western Europe exacerbated their situation. Furthermore, Axis units in the area were depleted by months of fighting, especially those which had taken part in the struggle for Stalingrad. The Germans could only count on the XXXXVIII Panzer Corps, which had the strength of a single panzer division, and the 29th Panzergrenadier Division as reserves to bolster their Romanian allies guarding the German Sixth Army's flanks. These Romanian armies lacked the heavy equipment to deal with Soviet armor. In contrast, the Red Army deployed over one million personnel for the offensive. Soviet troop movements were not without problems: concealing their build-up proved difficult, and Soviet units commonly arrived late due to logistical issues. Operation Uranus was first postponed by the Soviet high command (Stavka) from 8 to 17 November, then to 19 November.

At 07:20 Moscow time on 19 November, Soviet forces assaulted the northern flank of the Axis forces at Stalingrad; attacks in the south began the next day. Although the Romanian units succeeded in repelling the first Soviet attacks, by the end of 20 November the Third and Fourth Romanian armies were in headlong retreat, as the Red Army bypassed several German infantry divisions. German mobile reserves proved too weak to parry the Soviet mechanized spearheads, while the Sixth Army did not react quickly or decisively enough to disengage German armored forces in Stalingrad and re-orient them to countering the impending threat. By late 22 November, the northern and southern Soviet forces linked up at the town of Kalach, encircling some 290,000 Axis personnel east of the Don River. Instead of attempting to break out of the encirclement, German leader Adolf Hitler decided to keep Axis forces in Stalingrad and to resupply them by air.

The Battle of Stalingrad (23 August 1942 – 2 February 1943) was a major battle on the Eastern Front of World War II where Nazi Germany and its allies unsuccessfully fought the Soviet Union for control of the city of Stalingrad (later renamed to Volgograd) in Southern Russia. The battle was marked by fierce close-quarters combat and direct assaults on civilians in air raids. The Battle of Stalingrad was the deadliest battle to take place during the Second World War and is one of the bloodiest battles in the history of warfare, with an estimated 2 million total casualties. Today, the Battle of Stalingrad is universally regarded as the turning point in the European Theatre of war, as it forced the Oberkommando der Wehrmacht (German High Command) to withdraw considerable military forces from other areas in occupied Europe to replace German losses on the Eastern Front. The victory at Stalingrad energized the Red Army and shifted the balance of power in the favour of the Soviets.

Stalingrad was strategically important to both sides as a major industrial and transport hub on the Volga River. Whoever controlled Stalingrad would have access to the oil fields of the Caucasus; and control of the Volga. Germany, already operating on dwindling fuel supplies focused its efforts on moving deeper into Soviet territory and taking the oil fields at any cost. On 4 August, the Germans launched an offensive by using the 6th Army and elements of the 4th Panzer Army. The attack was supported by intense Luftwaffe bombing that reduced much of the city to rubble. The battle degenerated into house-to-house fighting as both sides poured reinforcements into the city. By mid-November, the Germans, at great cost, had pushed the Soviet defenders back into narrow zones along the west bank of the river.

On 19 November, the Red Army launched Operation Uranus, a two-pronged attack targeting the weaker Romanian armies protecting the 6th Army's flanks. The Axis flanks were overrun and the 6th Army was cut off and surrounded in the Stalingrad area. Adolf Hitler was determined to hold the city at all costs and forbade the 6th Army from attempting a breakout; instead, attempts were made to supply it by air and to break the encirclement from the outside. The Soviets were successful in denying the Germans the ability to resupply through the air which strained the German forces to their breaking point. Nevertheless the German forces were determined to continue their advance and heavy fighting continued for another two months. On 2 February 1943, the German 6th army, having exhausted their ammunition and food, finally capitulated, making it the first of Hitler's field armies to surrender during World War II, after five months, one week, and three days of fighting.