Why was the German assault of Stalingrad a crushing defeat for the Germans?

The German assault on Stalingrad resulted in a crushing defeat due to a combination of fierce Soviet resistance, harsh winter conditions, and overextended supply lines. The Red Army encircled the German Sixth Army in November 1942, cutting off their supplies and reinforcements. This strategic encirclement, coupled with the relentless Soviet counteroffensive, led to the surrender of approximately 91,000 German troops in February 1943, marking a significant turning point in World War II. The defeat weakened German morale and shifted the momentum of the war in favor of the Allies.