How did the Russians defeat the Germans at stalingrand?

The Russians defeated the Germans with the blessings of Ol' Man Winter and the follies of Adolph Hitler. The Germans were frozen, starving, dying from the cold and lack of food and supplies. At the end of the Stalingrad Battle a bunch of simple grenades did the trick. Many Germans were taken prisoner as they surrendered in defeat. Adolph Hitler can be blamed for the demise of the German forces failing. He refused to let them quit and he would not send more supplies.