The Battle of Kursk, involving some 6,000 tanks, two million men, and 5,000 aircraft, ends with the German offensive repulsed by the Soviets at heavy cost. In early July, Germany and the USSR concentrated their forces near the city of Kursk in western Russia, site of a 150-mile-wide Soviet pocket that jutted 100 miles into the German lines. The German attack began on July 5, and 38 divisions, nearly half of which were armored, began moving from the south and the north. However, the Soviets had better tanks and air support than in previous battles, and in bitter fighting Soviet antitank artillery destroyed as much as 40 percent of the German armor, which included their new Mark VI Tiger tanks. After six days of warfare concentrated near Prokhorovka, south of Kursk, the German Field Marshal Gunther von Kluge called off the offensive, and by July 23 the Soviets had forced the Germans back to their original positions. In the beginning of August, the Soviets began a major offensive around the Kursk salient, and within a few weeks the Germans were in retreat all along the eastern front.