Battle of Kursk guns and mortars. In 1943 an offensive by the Soviet Central, Bryansk and Western Fronts against Army Group Centre was abandoned shortly after it began in early March, when the southern flank of the Central Front was threatened by Army Group South. Soviet intelligence received information about German troop concentrations spotted at Orel and Kharkov, as well as details of an intended German offensive in the Kursk sector through the Lucy spy ring in Switzerland. The Soviets verified the intelligence via their spy in Britain, John Cairncross, at the Government Code and Cypher School at Bletchley Park, who clandestinely forwarded
Battle of Prokhorovka Kursk salient, becoming the first time in the Second World War that a major German offensive was halted before it could break through enemy defences and penetrate into their operational or strategic depths. With the end of Operation Citadel, the strategic initiative permanently swung over to the Soviet Union for the rest of the war. The battle has been widely described as the largest tank engagement or battle in military history, involving 1,200–1,500 tanks and sometimes up to 2,000, but this is incorrect as the battle did not involve that many tanks. The exaggerated figures originated from erroneous Soviet intelligence