Operation Uranus Operation " Uranus " ( ) was the codename of the Soviet 19 – 23 November 1942 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 in 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 that its forces in the southern Soviet Union were overstretched near Stalingrad , using weaker Romanian troops 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 . Due to 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 exacerbated by the German 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 allies 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 , due to the difficulties of concealing their build - up , and to Soviet units commonly arriving late due to logistical issues . Operation " Uranus " was first postponed from 8 to 17 November , then 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 to break out of the encirclement , 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 . Background . On 28 June 1942 , the Wehrmacht began its offensive against Soviet forces opposite of Army Group South , codenamed Case Blue . After breaking through Red Army forces by 13 July , German forces encircled and captured the city of Rostov . Following the fall of Rostov , Hitler split German forces operating in the southern extremity of the southern Russian SFSR in an effort to simultaneously capture the city of Stalingrad and the Caucasus oil fields . The responsibility to take Stalingrad was given to the Sixth Army , which immediately turned towards the Volga River and began its advance with heavy air support from the " Luftwaffe ' s " " Luftflotte 4 " . On 7 August , two German panzer corps were able to flank and encircle a Soviet force of 50 , 000 personnel and approximately 1 , 000 tanks , and on 22 August German forces began to cross the Don River to complete the advance towards the Volga . The following day , the Battle of Stalingrad began when vanguards of the Sixth Army penetrated the suburbs of the city . By November the Sixth Army had occupied most of Stalingrad , pushing the defending Red Army to the banks of the Volga River . By this stage , there were indications of an impending Soviet offensive which would target Wehrmacht forces around the city , including increased Soviet activity opposite the Sixth Army ' s flanks , and information gained through the interrogation of Soviet prisoners . However , the German command was intent upon finalizing its capture of Stalingrad . In fact , head of Army General Staff General Franz Halder had been dismissed in September after his efforts to warn about the danger which was developing along the over - extended flanks of the Sixth Army and the Fourth Panzer Army . As early as September the Soviet " Stavka " ( high command ) began planning a series of counteroffensives to encompass the destruction of German forces in the south , fighting in Stalingrad and in the Caucasus , and against Army Group Center . Ultimately , command of Soviet efforts to relieve Stalingrad was put under the leadership of General Aleksandr Vasilevsky . The " Stavka " developed two major operations to be conducted against Axis forces near Stalingrad , " Uranus " and " Saturn " , and also planned for Operation " Mars " designed to engage German Army Group Center in an effort to distract reinforcements and to inflict as much damage as possible . Operation " Uranus " involved the use of large Soviet mechanized and infantry forces to encircle German and other Axis forces directly around Stalingrad . As preparations for the offensive commenced , the attack ' s starting points were positioned on stretches of front to the rear of the German Sixth Army , largely preventing the Germans from reinforcing those sectors quickly where Axis units were too overstretched to occupy effectively . The offensive was a double envelopment ; Soviet mechanized forces would penetrate deep into the German rear , while another attack would be made closer to the German Sixth Army in an effort to attack German units there directly in the rear . While the Red Army prepared , the German high commanders — influenced by their belief that the Red Army , building up opposite Germany Army Group Center to the north , was incapable of mounting a simultaneous offensive in the south — continued to deny the possibility of an impending Soviet offensive . Comparison of forces . Axis forces involved . Case Blue involved German and other Axis forces sprawled out across a front over wide and several hundred kilometers deep , while the decision to conquer Stalingrad had stretched Axis forces even more thinly by drawing away personnel eastwards . For example , in early July the Sixth Army was defending a line , while also committing to an offensive which involved a distance of around . Army Group B , which was split from Army Group South ( the forces operating around the Caucasus were named Army Group A ) , seemed strong on paper : it included the Second and Sixth German , Fourth " Panzer " , Fourth and Third Romanian , Eighth Italian , and Second Hungarian Armies . Army Group B had the 48th Panzer Corps , which had the strength of a weakened panzer division , and a single infantry division as reserves . For the most part the German flanks were held by arriving non - German Axis armies , while German forces were used to spearhead continued operations in Stalingrad and in the Caucasus . While Adolf Hitler expressed confidence in the ability of non - German Axis units to protect German flanks , in reality these units relied on largely obsolete equipment and horse - drawn artillery , while in many cases the harsh treatment of enlisted personnel by officers caused poor morale . In regard to mechanization , the First Romanian Armored Division was equipped with around 100 Czech - built Panzer 35 ( t ) tank s , armed with a gun ineffective against the armor of Soviet T - 34 tanks . Similarly , their PaK anti - tank guns were also antiquated and they were largely short of ammunition . Only after repeated requests did the Germans send the Romanian units PaK guns ; six per division . These units were extended over very large sections of front ; for example , the Third Romanian Army occupied a line long , while the Fourth Romanian Army protected a line no less than long . The Italians and Hungarians were positioned at the Don west of the Third Romanian Army , but the German commanders did not hold in high regard the capability of those units to fight . Italian soldiers were sometimes held in low regard by their allies , but their ineffectiveness in combat was actually only due to their obsolete weaponry and poor equipment . Weapons in Italian service were of very low quality : they possessed almost no anti - tank weapons , hand grenades rarely detonated , the praised high - quality Italian submachine guns were extremely rare , and mortars and field artillery pieces were inadequate . Rifles and machine guns had to be heated for a long time on a fire to work properly in extreme climatic conditions , and often not capable of firing in the midst of battle . Generally , German forces were in no better shape ; they were weakened by months of fighting the Red Army , and , while " Stavka " raised new armies , the German high command attempted to maintain its existing mechanized units . Furthermore , during the course of the German offensive between May and November 1942 , two motorized divisions , the elite Leibstandarte and the Großdeutschland , were redeployed from Army Group A to the West , to provide a mechanized reserve in case of an Allied landing in France . The Sixth Army had also suffered many casualties during the fighting in the city of Stalingrad proper . In some cases , such as that of the 22nd Panzer Division , their equipment was no better than that of the First Romanian Armored Division . German formations were also overextended along large stretches of front ; the XI Army Corps , for example , had to defend a front around long . Soviet forces involved . The Red Army allocated an estimated 1 , 100 , 000 personnel , 804 tanks , 13 , 400 artillery pieces and over 1 , 000 aircraft for the upcoming offensive . Across the Third Romanian Army , the Soviets placed the redeployed 5th Tank Army , as well as the 21st and 65th Armies , in order to penetrate and overrun the German flanks . The German southern flank was targeted by the Stalingrad Front ' s 51st and 57th Armies , led by the 13th and 4th Mechanized Corps ; these would punch through the Fourth Romanian Army , in order to link up with the 5th Tank Army near the town of Kalach . In total , the Soviets had amassed 11 armies and various independent tank brigades and corps . Preparations for the offensive were , however , far from perfect ; on 8 November , " Stavka " issued orders to postpone the launch date of the operation , because transportation delays had prevented many units from being able to move into place . In the meantime , units at the front went through a number of war games to practice repelling an enemy counterattack and exploiting a breakthrough with mechanized forces . These movements were masked through a deception campaign by the Soviets , including the decrease of radio traffic , camouflage , operational security , using couriers for communication instead of radio , and active deception , such as increasing troop movements around Moscow . Troops were ordered to build defensive fortifications , to offer false impressions to the Germans , while fake bridges were put up to divert attention from the real bridges being built across the Don River . The Red Army also stepped up attacks against Army Group Center and set up dummy formations to maintain the idea of a main offensive against German forces in the center of the Soviet Union . The Soviet Stalingrad Front forces were subject to heavy bombardment , making mobilization more difficult . The 38 engineer battalions allocated to the front were responsible for ferrying ammunition , personnel and tanks across the Volga River while carrying out minor reconnaissance along sections of the front which were to be the breakthrough points of the impending offensive . In three weeks the Red Army transported around 111 , 000 soldiers , 420 tanks and 556 artillery pieces across the Volga . On 17 November Vasilevsky was recalled to Moscow , where he was shown a letter written to Stalin by General Volsky , commander of the 4th Mechanized Corps , who urged calling off the offensive . Volsky believed the offensive as planned was doomed to failure due to the state of the forces earmarked for the operation ; he suggested postponing the offensive and redesigning it entirely . Many Soviet soldiers had not been issued with winter garments , and many died of frostbite , " due to the irresponsible attitude of commanders " . Although Soviet intelligence made honest efforts to collect as much information as possible on the disposition of the Axis forces arrayed in front of them , there was not much information on the state of the German Sixth Army . The Soviet commanders , overruling Vasilevsky , agreed the offensive would not be called off , and Stalin personally rang Volsky , who reiterated his intention to carry out the operation if ordered to do so . Soviet offensive . Operation " Uranus " , postponed until 17 November , was again postponed for two days when Soviet General Georgy Zhukov was told the air units allotted to the operation were not ready ; it was finally launched on 19 November . Shortly after 5 a . m . Lieutenant Gerhard Stöck , posted with the Romanian IV Army Corps on the Kletskaya sector called Sixth Army headquarters housed in Golubinsky , offering intelligence on a pending attack which would occur after 05 : 00 that morning ; however , because his call had come in after five and false alarms were common during this time , the duty officer on the other end of the line was not keen on waking the Army Chief of Staff , General Arthur Schmidt . Although Soviet commanders suggested postponing the bombardment due to poor visibility due to thick fog , front headquarters decided to proceed . At 07 : 20 Moscow time ( 05 : 20 German time ) Soviet artillery commanders received the codeword " Siren " , prompting an 80 - minute artillery bombardment directed almost entirely against the non - German Axis units protecting the German flanks . Some 3 , 500 guns opened up against the Third Romanian Army and the northern shoulder of the German Sixth Army ' s flank . Although thick fog prevented the Soviet artillery from correcting their aim , their weeks of preparation and ranging allowed them to lay down accurate fire on enemy positions along the front . The effect was devastating , as communication lines were breached , ammunition dumps destroyed and forward observation points shattered . Many Romanian personnel who survived the bombardment began to flee to the rear . Soviet heavy artillery aimed at Romanian artillery positions and second - echelon formations also caught the retreating Romanian soldiers . Against the Third Romanian Army : 19 November . The offensive against the Third Romanian Army began at 08 : 50 , led by the 21st and 65th Soviet Armies and the 5th Tank Army . The first two assaults were repulsed by the Romanian defenders , and the effects of the heavy artillery bombardment had actually made it more difficult for Soviet armor to navigate through the minefields and terrain . However , the lack of heavy anti - tank artillery caused the Romanian defense to collapse ; a breakthrough by the 4th Tank Corps and 3rd Guards Cavalry Corps was established by noon . Soon after , the 5th Tank Army was able to gain a breakthrough against the Second Romanian Corps , followed by the Eighth Cavalry Corps . As Soviet armor navigated through the thick fog by compass , overrunning Romanian and German artillery positions , three Romanian infantry divisions began to fall back in disarray ; the Third Romanian Army had been outflanked to the West and East . After receiving the news of the Soviet attack , Sixth Army headquarters failed to order the 16th and 24th Panzer Divisions , hitherto engaged in Stalingrad , to reorient themselves to bolster the Romanian defenses ; instead the task was given to the seriously understrength and poorly equipped 48th Panzer Corps . The 48th Panzer Corps had fewer than 100 serviceable modern tanks to combat Russian armor . Furthermore , they lacked fuel , and the shortage of tanks forced commanders to organize tank crews into infantry companies ; the 22nd Panzer Division , which formed part of the corps , was almost completely destroyed in the fighting that ensued . The 22nd had entered the fighting with fewer than thirty working tanks , and left with a company of tanks . The Romanian 1st Armored Division , attached to the 48th Panzer Corps , engaged the Soviet 26th Tank Corps after having lost communications with their German corps commanders , and were defeated by 20 November . As the Soviets continued to advance southwards , many Soviet tank crews began to suffer from the worsening blizzard , which affected men and equipment , and blocked gunsights . It was not uncommon for tanks to lose traction on the ground , and for a crew member to have an arm broken as he was thrown around inside the hull . However , the blizzard also neutralized the German corps ' coordination . The Third Romanian Army began to be routed by the end of 19 November . The Soviet 21st Army and 5th Tank Army were able to capture some 27 , 000 Romanian prisoners — the bulk of three divisions — and then continue their advance southwards . Soviet cavalry was used to exploit the breakthrough , sever communications between the Romanians and the Italian 8th Army , and to block any possible counterattack against the Soviet flank . While the Red Air Force strafed retreating Romanian soldiers , the " Luftwaffe " provided only negligible opposition . The withdrawal of the 1st Romanian Cavalry Division , originally positioned on the German 376th Infantry Division ' s flank , allowed the 65th Army to bypass German defenses . As German forces began to react late on 19 November , another attack developed on the Sixth Army ' s flank to the south . Against the German southern flank : 20 November . In the early morning of 20 November " Stavka " telephoned Stalingrad Front commander Andrei Yeremenko asking if he would begin his portion of the offensive on schedule , at 08 : 00 . He responded he would do so only if the fog lifted ; although the 51st Army opened its artillery barrage on time because front headquarters could not contact the division , the rest of the forces prepared for the operation received orders to postpone the attack until 10 : 00 . The 51st Army engaged the Romanian 6th Corps , taking many prisoners . As the 57th Army joined the attack at 10 : 00 , the situation developed in such a way that the Stalingrad Front could throw its armored corps into battle . The German 297th Infantry Division watched as its Romanian support failed to put up resistance against the Red Army . However , confusion and lack of control caused the Soviet 4th and 13th Mechanized Corps to stumble as they began to exploit the breakthroughs achieved by the opening offensive . The Germans responded quickly by redeploying their only reserve in the area , the 29th Panzergrenadier Division . Despite initial victories against Soviet armored forces , the Romanian collapse forced the division to again redeploy in an attempt to shore up defenses to the south . The 29th Panzergrenadier Division ' s counterattack had cost the Red Army around fifty tanks , and caused Soviet commanders to worry about the safety of their left flank . However , the German division ' s redeployment meant that by the end of the day only the 6th Romanian Cavalry Regiment was positioned between advancing Soviet forces and the Don River . Continued operations : 20 – 23 November . While the Stalingrad Front launched its offensive on 20 November , the 65th Soviet Army continued to apply pressure to the German 11th Corps along the northern shoulder of the Sixth Army ' s flank . The Red Army ' s 4th Tank Corps advanced beyond the German 11th Corps , while the 3rd Guards Cavalry Corps crashed into the German unit ' s rear . The German 376th Infantry Division and the Austrian 44th Infantry Division began to redeploy to face the enemy on their flanks , but were hindered by shortage of fuel . The 14th Panzer Division ' s remaining panzer regiment destroyed a flanking regiment of the Soviet 3rd Guards Cavalry Corps , but its anti - tank artillery suffered heavy casualties when it was overrun by Soviet forces . By the end of the day the Soviet 1st Tank Corps was chasing the retreating 48th Panzer Corps , while the Soviet 26th Tank Corps had captured the town of Perelazovsky , almost to the northwest of Stalingrad . The Red Army ' s offensive continued on 21 November , with forces of the Stalingrad Front achieving penetrations of up to . By this time remaining Romanian units in the north were being destroyed in isolated battles , while the Red Army began to engage flanking portions of the German Fourth Panzer and Sixth Armies . The German 22nd Panzer Division , despite attempting a short counterattack , was reduced to little more than a tank company and forced to withdraw to the southwest . The Soviet 26th Tank Corps , having destroyed a large portion of the Romanian 1st Armored Division , continued its advance to the southeast , avoiding engaging enemy left behind , although remnants of the Romanian 5th Corps were able to reorganize and put up a hastily constructed defense in the hope that it would be aided by the German 48th Panzer Corps . That day German General Friedrich Paulus , commander of the Sixth Army , received reports that the Soviets were less than from his headquarters ; furthermore , there were no remaining units which could contest the Soviet advance . In the south , after a brief halt , the Soviet 4th Mechanized Corps continued its advance north , removing German defenders from several towns in the area , towards Stalingrad . As German forces in and around Stalingrad were at risk , Hitler ordered German forces in the area to establish an " all - around defensive position " and designated forces between the Don and Volga rivers as " Fortress Stalingrad " , rather than allow the Sixth Army to attempt to break out . The Sixth Army , other Axis units , and most of the Fourth Panzer Army ' s German units were caught inside the growing Soviet encirclement . Only the 16th Panzergrenadier Division began to fight its way out . Lack of coordination between Soviet tanks and infantry as the Red Army ' s tank corps attempted to exploit the breakthrough along the Germans ' southern flank allowed much of the Fourth Romanian Army to escape destruction . On 22 November Soviet forces began to cross the Don River and continued their advance towards the town of Kalach . German forces defending Kalach , mostly composed of maintenance and supply personnel , were not aware of the Soviet offensive until 21 November , and even then did not know in what strength the Red Army was approaching . The task of taking the bridge at Kalach was given to the Soviet 26th Tank Corps , which used two captured German tanks and a reconnaissance vehicle to approach it and fire on the guards . Soviet forces broke into the town by mid - morning and drove the defenders out , allowing themselves and the 4th Tank Corps to link up with the Red Army ' s 4th Mechanized Corps approaching from the south . The encirclement of German forces in Stalingrad was completed on 22 November 1942 . That day Soviet formations also continued to fight pockets of Romanian resistance , such as that put up by the Romanian 5th Corps . Fighting continued on 23 November as the Germans attempted in vain to mount local counterattacks to break the encirclement . By this time Axis personnel inside the encirclement moved east towards Stalingrad to avoid Soviet tanks , while those that managed to escape the encirclement moved west toward German and other Axis forces . Aftermath . Operation " Uranus " trapped between 250 , 000 and 300 , 000 Axis soldiers within an area stretching from east to west and north to south . The pocket contained four infantry corps , a panzer corps belonging to the Fourth Panzer and Sixth Armies , and surviving elements of two Romanian divisions , a Croat infantry regiment and other specialist units . Trapped equipment included around 100 tanks , 2 , 000 artillery pieces and mortars and 10 , 000 trucks . The withdrawal to Stalingrad left lines of retreat littered with helmets , weapons and other equipment , and heavy equipment which had been destroyed was left on the side of the road . Bridges spanning the Don River were jammed with traffic , as surviving Axis soldiers hastily made their way eastwards in the cold weather , attempting to escape Soviet armor and infantry threatening to cut them off from Stalingrad . Many wounded Axis personnel were trampled , and many of those who attempted to cross the river on foot on the ice fell through and drowned . Hungry soldiers filled Russian villages scouring for supplies , while supply dumps were often looted in search of cans of food . The last stragglers crossed the Don River by 24 November , and demolished the bridges to seal off the Fourth Panzer and Sixth Armies from the Soviets in Stalingrad . The Sixth Army , in the midst of chaos , began to build defensive lines , hampered by the lack of fuel , ammunition and rations , and further burdened by the advancing Russian winter . It was also tasked with plugging gaps in the line caused by the disintegrating Romanian forces . On 23 November , some German units destroyed or burned everything not necessary for a breakout operation and began to pull back towards the northern end of Stalingrad . However , after the Germans had abandoned their winter bunkers , the Soviet 62nd Army was able to destroy the German 94th Infantry Division on the open ground ; survivors of the German division were attached to the 16th and 24th Panzer Divisions . Although German military commanders were of the opinion that Wehrmacht forces caught in the encirclement should break out , between 23 and 24 November Hitler decided instead to hold the position and attempt to resupply the Sixth Army by air . The personnel trapped in Stalingrad would require at least of supplies per day , a task which the depleted " Luftwaffe " was actually in no condition to carry out . Furthermore , the revived Red Air Force was a threat to German aircraft attempting to fly over the encirclement . Although by December the " Luftwaffe " had assembled a fleet of around 500 aircraft , this was still insufficient to supply the Sixth Army and elements of the Fourth Panzer Army with the required supplies . During the first half of December the Sixth Army received less than 20 % of their daily requirements . In the meantime , the Red Army strengthened its outer encirclement with the intention of destroying the encircled German units . Soviet armies would attack German units to the east and the south , aiming to split German units into smaller groups . These orders became effective on 24 November , and were to be executed without a major regrouping or movement of reserves . The outer encirclement ran for an estimated , although only three - quarters of that distance was actually covered by Soviet troops ; the distance between the outer and inner encirclements was around . The Soviet high command also began planning for Operation " Saturn " , which was aimed at destroying the Italian Eighth Army and cutting off German forces in the Caucasus . The Soviet " Stavka " planned " Saturn " to start on about 10 December . German forces in the area had been further split up , as German general Erich von Manstein was given command of the newly created Army Group Don , comprising the German Fourth Panzer and Sixth Armies , and the Third and Fourth Romanian Armies . Although the situation looked bleak for the Germans , a moment of relative calm had settled after the end of Operation " Uranus " ; German and Soviet forces were planning their next movements .