The problem with FM Paulus, the commander of the Sixth Army at Stalingrad, was that really was intimidated by Hitler and a total Hitler loyalist. He knew from the outset he had to break out of the Soviet trap immediately. But Hitler ordered him to stay put. FM von Manstein urged him to break out and defy Hitler, but Paulus was too timid to defy Hitler and always obeyed Hitler no matter what, except at the very end, when on just about the last day of the battle, Hitler promoted him to field marshall with the expectation he would commit suicide. For the first time, Paulus refused Hitler and surrendered his army and went into Soviet captivity. While in captivity Paulus turned against Hitler completely and became part of a Soviet propaganda effort aimed at encouraging German troops to give up and surrender.
How interesting that after the Casablanca trip, Churchill watched the movie, Casablanca.