From Glantz and House, Armageddon in Stalingrad:
The two weeks of bloody [September] fighting in the streets and rubble of Stalingrad... established the parameters for... the fate of Army Group B and Operation Blau as a whole. Weichs and Paulus had planned for a triumphant march... tanks, assault guns, and accompanying panzer-grenadiers and landsers enveloping it form the north and south. Instead... a painfully slow, grinding, and immensely costly block-to-block and building-to-building slugging match....
Stalin's decision to defend the city deprived the Germans of their traditional advantages of mobility, maneuver, and precise, overwhelming, and deadly artillery and air support. This forced thei attackers to gnaw their way through Chuikov's defense in a battle that resembled... Verdun... more than it did the familiar blitzkrieg.... Although imposed on them by Hitler, Weichs's and Paulus's decision to take Stalingrad by storm negated all the Germans' traditional advantages and committed Sixth Army to a struggle it could not win....
[T]he fighting in Stalingrad was only one element in the strategy Stalin and the Stavka had been pursuing since late July 1942. Their intent was to halt or at least slow down the momentum... sufficiently to permit the Red Army to conduct a massive counteroffensive against Axis forces when they became overextended.... By mid-September... Hitler's dcision to seize Stalingrad by storm stripped the momentum from Sixth Army's grasp, putting it instead into the REd Army's hands. From the perspective of Stalin and the Stavka, the cold-hearted sacrifice of Chuikov's 50000 men in the streets and ruins of Stalingrad, plus whatever reinforcements were required... was a small price to pay for victory by the million-plus men who would conduct the Red Army's counteroffensive....
Each piece in the mosaic... played a vital role in this strategy. Paulus's assault on Stalingrad committed his troops to a paralyzing set-piece battle... would force Sixth Army to weaken its defenses in other key sectors by replacing veteran German troops with inexperienced Italian and Romanian troops. The brutal, repetitive offensives... in the Kotluban'... deprive[ed Paulus] of his planned northern pincer--XIV Panzer Corps....
Once locked in the deadly spiral inside the city, Sixth Army's shock groups suffered so many casualties that Paulus was forced to send a steady stream of fresh divisions in to the Soviet meat grinder... at the expenses of the defenses on Army Group B's left wing. All the while, the armored strength of Paulus's army--the motive force that had propelled it to Stalingrad in the fist place--dwindled dramatically... raising the specter of catastrophic defeat when and if the Red Army learned to employ effectively its seemingly endless supply of tanks and tank crews....
Facing these grim prospects but not yet fully aware of the ultimate consequences, Paulus... prepared his shock groups....
On the other side of the hill, Chuikov's 62nd Army prepared to continue its deadly but vital work in the ruins of Stalingrad's factories and workers' villages.
