The Battle of Stalingrad
The Nazis invade the oil rich Caucasus to cut off this critical source of fuel to the Soviets. Standing in the way is Staligrad. Without realizing the strategic error they are making the Nazis reduce the city to rubble through air and artillery bombardment. The rubble serves as an ideal environment for an extended urban battle where the vaunted Blitzkrieg is useless. The error costs the Nazis dearly in men and materiel which the Nazis need for the Battle of Moscow and time the Soviet’s use to rearm. Worst, The Nazis fail in their objective to capture the Caucuses.