How was the battle of Stalingrad affected by geography?

Stalingrad was part of the German front in southern Russia and part of a larger operation that also had as a target the Caucasus. The German front was simply overextended and as the battle raged and went on into the first months of 1943, its flanks - running up to 400 miles to both north and south - were exposed and undermanned. The distances were too long and this posed a major logistic problem for German units.