On the morning of 5 July 1943, the Wehrmacht launched its offensive, Operation Citadel, against the Soviet forces defending the Kursk salient. They made slow but steady progress through the Soviet defensive lines. After a week of fighting, the Soviets launched a major counterattack, which resulted in one of the largest clashes of armoured forces, the Battle of Prokhorovka. The attacking Soviet forces were decimated in the battle, but they succeeded in preventing the Wehrmacht from capturing Prokhorovka and breaking through the third defensive belt – the last heavily fortified one.