Before the Soviets could engage
Paulus, they had to rout the Rumanians camped north and south of Stalingrad. Part of the Russian contingent would swoop down from the north; the other would move up from the south. They would meet in the middle, at the Kalach area. (This fantastic animated map from a great German web site is worth the load wait.)
At first, the Rumanians did not believe the shaking ground was caused by an
initial salvo from Russian Katyusha rockets and T-34 tanks. With morning fog hiding the truth on November 19th, it was easy to disregard warnings of an impending attack. When the fog cleared, panic ensued. Frantic calls to the Sixth Army were taken seriously, but no one believed the Soviet threat would lead to disaster.
Front lines, stationery for so many weeks, now changed daily. Hitler, refusing to believe his men were
trapped, would not allow Paulus to escape or surrender. Paulus was hemmed in. He could only move between the northern and southern sections of the besieged city.
By the middle of December, the Germans planned their own attack, called "Operation Winter Storm." Trying to break free between December 12 and 18, their efforts produced little more than frustration. Zhukov, Vasilevsky and Voronov had outwitted the men of the Third Reich (Follow the link to a terrific animated map from the Hungarian University of Szeged and, once it’s loaded, you can track the course of the Soviet counter attack.) Stalin was Time Magazine's 1942 Man of the Year!.
By January 8, 1943 the Soviets offered Paulus surrender terms. He refused. At the end of January, sensing the situation was
hopeless, Hitler promoted Friedrich Paulus to Field Marshall. His reason? A not-so-subtle reminder that no German Field Marshall had ever surrendered.
Paulus had only one option, according to the Fuhrer: commit suicide.