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 Kursk the salient. Red Army combat engineers laid 503,663 anti-tank mines and 439,348 anti-personnel mines, with the highest concentration in the first main defensive belt. The minefields at Kursk achieved densities of 1,700 anti-personnel and 1,500 anti-tank mines per kilometre, about four times the density used in the defence of Moscow. For example, the 6th Guards Army of the Voronezh Front, was spread out over nearly of front and was protected by 69,688 anti-tank and 64,430 anti-personnel mines in its first defensive belt with a further 20,200 anti-tank and 9,097 anti-personnel mines in its second defensive belt. Furthermore, mobile obstacle detachments