For those who don't know, Stalingrad is a city on the western bank of the Volga river. Just south of it, there's an island along the river, and a few km further south a series of salt water lakes.
When the germans attacked the city, they reached the Volga river north of the city, installed gun batteries to prevent soviet ships getting trough, however, they did not push in the south, where they could at least do the same, or even possibly launch an attack to take the island, thus totally cutting of soviet shipping that kept the city alive. Instead, they tried this with artillery and air attacks. Since the germans where far better of in the open filed, due to air support and superior tactics, why didn't they push south to cut off the city ? I for one have no ideea other than maybe the incompetence of von Paulus. Any thoughts ?