Urban combat is grueling. Compared to other types of terrain it requires very high troop densities, it reduces the effectiveness of artillery and air support, it reduces the maneuverability and survivability of armor, it produces unbelievably high casualty rates, and it exhausts troops very quickly, both mentally & physically. As a point of comparison, the Russian Army found during the 1995 Battle of Grozny that frontline troops needed to be rotated out for rest after only a few hours of actual combat. The prize for all of these costs? Slow rates of advance, sometimes measured in tens of meters a day. General Hans Doerr, the chief of the General Staff of the LII Corps at Stalingrad, later wrote that "the meter replaced the kilometer as a measure of distance, and the city plan replaced the General Staffs map." In practical terms, there is no such thing as a short city fight. This experience has been affirmed in every urban battle from Jerusalem (1099) to Idlib (ongoing). An 1862 diary entry from one Col. Norman Hall of the 17th Michigan Volunteer Infantry Regiment, describing his experience at Fredericksburg, has proven prescient one hundred and sixty years later.

The Rebels could only be dislodged by desperate fighting among the buildings of the town. It was impossible and impracticable to attempt to relieve the press by throwing troops into the streets, where they could only be shot down, unable to return the fire. The Rebels fired on us from windows and doors and from behind houses. We had no choice but to rush the houses, breaking in doors to drive them from the town. My regiments did not falter, but in future I should much prefer to fight in open fields, than amid buildings and town streets.

The brutal reality of urban war was exacerbated by both sides' preexisting exhaustion. The Wehrmacht had reached the end of its logistical tether by the time it arrived at Stalingrad in August. Paulus' 6th Army had had to take a 10-day operational pause at the end of July to refuel, and deficiencies in supplies like spare parts and medical supplies would dog 6th Army until the bitter end. Worse for the Wehrmacht, casualties from 1941 had not been fully replaced. Army Group South had received the lion's share of replenishment at the expense of Army Groups North and Center, which had to refit their recon units with bicycles and pare down the number of infantry battalions per division by a third. Even by robbing Peter to pay Paulus it was only possible to raise Army Group South's units to an average of 85% of their prescribed strength. On the other side of the map, the Soviets had been badly mauled in an encirclement at Kalach in the bend of the River Don, with the result that Chuikov's famed 62nd Army at Stalingrad had in fact only recently been reconstituted from reserves and other units when the battle started.

Stalingrad's geography played a role as well. Unlike many cities, which are more-or-less circular and radiate out into suburbs from a town center, Stalingrad was a long rectangular strip of factories and dense apartment blocks along the Volga river. This density and the proximity to the river favored the defender heavily, as the Soviets had a long 'beachhead' on which to land reinforcements. The sloping banks of the Volga also provided good entrenchment terrain for the Red Army to dig into. On the far bank of the river, Soviet artillery could mass relatively unmolested.

All of these factors combined to produce a long, slogging, knock-down drag-out fight within the city. After Operation Uranus broke the German lines and surrounded the city in November, the same factors that gave the Red Army such defensive tenacity would go on to give the surrounded 6th Army remarkable staying power as the Soviets worked for two months to finish off the pocket.