These howitzers were ordered in 1916 from Schneider et Cie, but development was protracted and the first weapon wasn't delivered until late 1917. They used a combination of cradle recoil and sliding recoil to handle the recoil forces generated by firing its enormous shells. A number of crossbeams mounted on the underside of the carriage were jacked down and clamped to the track to increase the friction when the carriage was forced backwards about a 1 metre (1.1 yd) from the recoil forces not absorbed by the hydraulic buffers on the gun cradle. The mount was then jacked up and then moved back into firing position by hand-crank or electric motor. The gun had to be loaded at 0° elevation and thus had to be re-aimed for every shot. A prominent overhead trolley system mounted behind the gun carried the ammunition to the breech from the ammunition car. It fired shells weighing 1,370 and 1,654 kilograms (3,000 and 3,600 lb). Elevation and ammunition handling were electrically-powered from a separate generator car connected by approximately 10 metres (11 yd) of cables.
The first howitzer was destroyed during firing trials at the range in Quiberon in July 1918 when a shell detonated prematurely in the barrel. The second gun was delivered in 1918, but didn't complete its firing trials before the war ended. It was placed in storage, but was not part of the French mobilization plans until after the war began so it needed to be renovated before it could be committed to battle. It was captured in the Schneider workshops before it could fire a single round in anger.
The Germans placed it into service as the 52 cm Haubitze (E) 871(f) (French railroad howitzer) and it was assigned to Railroad Artillery Battery (Artillerie-Batterie (E.)) 686. It didn't participate in the opening stages of Operation Barbarossa, but arrived on the outskirts of Leningrad on 21 November 1941. It was destroyed when a shell detonated in the barrel on 5 January 1942. The abandoned wreckage was captured by the Soviets during Operation Iskra in 1943.
Weight 263 tonnes (259 LT; 290 ST)
Length 30.38 m (99.7 ft)
Barrel length 11.9 m (39 ft) L/15
Shell weight 1,370 and 1,654 kg (3,000 and 3,600 lb)
Caliber 520 millimetres (20 in)
Breech interrupted screw
Carriage 2 x 8-axle trucks
Elevation +40° to +60° (firing)
Rate of fire 1 round per 6 minutes
Muzzle velocity 450 to 500 m/s (1,500 to 1,600 ft/s)
Maximum range 14,600 to 17,000 metres (16,000 to 18,600 yd)