35.5 cm Haubitze M1

35.5 cm Haubitze M1
The breech of a Haubitze M1 being lifted into position to be mated to the barrel
Type	Super-Heavy Siege Howitzer
Place of origin	Germany
Service history
In service	1939–45
Used by	Nazi Germany
Wars	World War II
Production history
Designer	Rheinmetall
Designed	1936–39
Manufacturer	Rheinmetall
Produced	1939–44
No. built	8
Specifications
Weight	75 tonnes (74 long tons; 83 short tons)
Barrel length	8.05 metres (317 in)
Shell	separate-loading, case charge
Shell weight	575 kilograms (1,268 lb)
Caliber	356 millimetres (14.0 in)
Breech	horizontal sliding-block
Recoil	hydro-pneumatic
Carriage	box
Elevation	+45° to 75° (firing)
Traverse	6° (on carriage) 360° (on platform)
Rate of fire	1 round per 4 minutes
Muzzle velocity	570 metres per second (1,900 ft/s)
Maximum firing range	20,850 metres (22,800 yd)
Filling	TNT and wax
Filling weight	7.94 kilograms (17.5 lb)

The 35.5 cm Haubitze M1 was a German siege howitzer. It was developed by Rheinmetall before World War II to meet the German Army's request for a super-heavy howitzer. Eight were produced between 1939 and 1944. It saw service in the Battle of France and spent the rest of the war on the Eastern Front, saw action in Operation Barbarossa, the Siege of Sevastopol, the Siege of Leningrad and helped to put down the Warsaw Uprising in 1944.

The Haubitze M1 was best described as an enlarged 24 cm Kanone 3. It used many of the same design principles as the smaller weapon including the dual-recoil system and a two-part carriage capable of all-around traverse when mounted on its firing platform. It also disassembled into six loads for transport. The loads were cradle, barrel, top carriage, bottom carriage, front platform and turntable and the rear platform. Each piece on its trailer was towed by a 18 t (18 long tons; 20 short tons) Sd.Kfz. 9 half-track. A seventh half-track towed the gantry crane required to assemble the weapon. The gantry crane (powered by a generator on its towing vehicle) would be erected at the new firing position and would take about two hours to assemble the entire weapon.

The howitzer's dual recoil system meant that the barrel in its ring cradle would recoil on the carriage while the carriage would recoil, in turn, on the firing platform. The recoil for both parts was controlled by hydro-pneumatic cylinders. Its elevation gear and ammunition hoist were electrically powered from the generator, although both could be used manually if necessary. Only a 575 kg (1,268 lb) concrete-piercing shell (Betongranate) with a ballistic cap was ever used by this weapon. It used 234.2 kilograms (516 lb) of propellant in four increments to reach a range of 20,850 metres (22,800 yd).