Battle of Stalingrad on Soviet records, over 10,000 German soldiers continued to resist in isolated groups within the city for the next month. Some have presumed that they were motivated by a belief that fighting on was better than a slow death in Soviet captivity. Brown University historian Omer Bartov claims they were motivated by National Socialism. He studied 11,237 letters sent by soldiers inside of Stalingrad between 20 December 1942 and 16 January 1943 to their families in Germany. Almost every letter expressed belief in Germany's ultimate victory and their willingness to fight and die at Stalingrad to achieve that victory. Bartov
Battle of Stalingrad later by General Maximilian von Weichs. The start of "Case Blue" had been planned for late May 1942. A number of German and Romanian units that were to take part in "Blau", however, were besieging Sevastopol on the Crimean Peninsula. Delays in ending the siege pushed back the start date for "Blau" several times, and the city did not fall until the end of June. Operation Fridericus I by the Germans against the "Isium bulge", pinched off the Soviet salient in the Second Battle of Kharkov, and resulted in the envelopment of a large Soviet force between 17 May and