Operation Uranus was the codename of the Soviet strategic operation in World War II which led to the encirclement of the German Sixth Army, the Third and Fourth Romanian armies, and portions of the German Fourth Panzer Army. The operation formed part of the ongoing Battle of Stalingrad, and was aimed at destroying German forces in and around Stalingrad. Planning for Operation Uranus had commenced as early as September 1942, and was developed simultaneously with plans to envelop and destroy German Army Group Center and German forces in the Caucasus. The Red Army took advantage of the German army's poor preparation for winter, and its forces in the southern Soviet Union were overstretched, using weaker Romanian, Hungarian, and Italian armies to guard their flanks; the offensives' starting points were established along the section of the front directly opposite Romanian forces. These Axis armies lacked heavy equipment to deal with Soviet armor.

Given the length of the front created by the German summer offensive, aimed at taking the Caucasus oil fields and the city of Stalingrad, German and other Axis forces were forced to guard sectors beyond the length they were meant to occupy. The situation was not improved by the decision to relocate several mechanized divisions from the Soviet Union to Western Europe. Furthermore, units in the area were depleted after months of fighting, especially those which took part in the fighting in Stalingrad. The Germans could only count on the 48th Panzer Corps, which had the strength of a single panzer division, and the 29th Panzergrenadier Division as reserves to bolster their Romanian supporters on the German Sixth Army's flanks. In comparison, the Red Army deployed over one million personnel for the purpose of beginning the offensive in and around Stalingrad. Soviet troop movements were not without problems; to avoid tipping off the Germans, the Soviets tried to conceal their build-up, which was difficult. Commonly, Soviet units arrived late because of logistical frustrations. Operation Uranus was originally postponed from 8 to 17 November, and later moved back to 19 November.

At 07:20 (Moscow time) on 19 November Soviet forces on the northern flank of the Axis forces at Stalingrad began their offensive; forces in the south began on 20 November. Although Romanian units were able to repel the first 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 were not strong enough to parry the Soviet mechanized spearheads, while the Sixth Army did not react quickly enough to disengage German armored forces in Stalingrad and reorient them to defeat the impending threat. By late 22 November Soviet forces linked up at the town of Kalach, encircling some 290,000 men east of the Don River. Instead of attempting a breakout operation, German dictator Adolf Hitler decided to keep Axis forces in Stalingrad and resupply them by air. In the meantime, Soviet and German commanders began to plan their next movements.

South-west front and Donfront Against the Third Romanian Army:

At 7.20 hrs November 19, 1942, Voronov's guns and mortars, 3500 of them, laid down
an eighty minute barrage against Rumanian IInd Army.
The barrage lifted and through the mist there came down on the dazed Rumanians
the Soviet infantry, wave upon wave, and with them the menacing shapes of the T-34,
over two hundred of them. The Rumanians broke and their divisions fell to pieces,
streaming in panic towards the rear.
Behind them the stolid Soviet Infantry plodded on, rounding up the pathetic
groups of fleeing Rumanians, while the mobile forces gathered themselves for their
next missions, towards the Don and Kalach.

Stalingrad front Against the German southern flank:

At 10.00 hrs on November 20 1942, 1000 Katyusha salvoes signalled the beginning
of the artillery bombardement. Yeremenko's attack was itself a two-pronged one.
On his right parts of 64th and 57th Armies with a force of six infantry divisions
would strike up towards the rear of the German 6th Army, and when they made a
the 13th Mechanised Corps would advance towards the Chervlenaya river to pen
in the Stalingrad force, while on his left 51st Army would make a hole through
which the 4th Mechanised Corps and the 4th Cavalry Corps would be launched
towards Sovetsky and on to Kalach, thus to forge the ring of encirclement around
the bulk of the German Army Group B.

Soviet strength at the beginning of Operation Uranus.