Operation Winter Storm (German: Unternehmen Wintergewitter) was a German offensive in World War II in which the German 4th Panzer Army unsuccessfully attempted to break the Soviet encirclement of the German 6th Army during the Battle of Stalingrad.In late November 1942, the Red Army completed Operation Uranus, encircling some 300,000 Axis personnel in and around the city of Stalingrad.