Although the German offensive at Kursk was probably a strategic fool's paradise, with little hope of causing the defeat of the Soviet Union even if the Germans had won, Adolf Hitler ensured a German defeat by critically weakening the force at the last moment.

As Western Allies had recently forced the Wehrmacht out of Africa, and were busy conquering Sicily, the people of Italy developed a sudden case of war fatigue.

Fascist leader Benito Mussolini was deposed on July 25. Hitler pulled a large number of German troops from the Kursk offensive to reinforce German positions in Italy.

Left to fight in their place were Axis troops from Hungary and Romania. These troops were less-experienced and less willing to die for the glory of a fictitious Aryan race they wouldn't have belonged to anyway.

Note: Most of this information comes from History Channel documentaries. I can find little on the Web to back it up.