The Battle of Kursk was one of the defining moments of World War II.
In July 1943, German forces under Erich von Manstein--one of Germany's best generals--launched a massive attack in an offensive code-named Citadel. A week later, the Soviets counterattacked, sparking a huge clash of tanks at Prokhorovka, the largest armor battle in history, pitting more than 600 Soviet tanks against some 300 German panzers.
Though the Germans gained a tactical victory, destroying huge numbers of Soviet tanks, they failed to achieve their objectives, and in the end the battle marked a turning point on the Eastern Front. The Red Army gained the strategic initiative and would not lose it.