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21 cm Mörser 18
Fancifully-painted Mrs 18 at the US Army Field Artillery Museum, Ft. Sill, OK
Type Heavy howitzer
Place of origin Germany
Service history
In service 1939–45
Used by Nazi Germany
Wars World War II
Production history
Designer Krupp
Manufacturer Krupp
Produced 1939–45
Number built 711+
Weight 16,700 kg (36,817 lbs)
Barrel length 6.51 m (21 ft 4 in) L/30

Shell separate-loading cased ammunition (6 charges)
Shell weight 113 kg (249 lb) (HE)
Caliber 211 mm (8.30 in)
Breech horizontal sliding block
Recoil dual-recoil hydropneumatic
Carriage box trail
Elevation -6° to +70°
Traverse 16° on wheels
360° on platform
Muzzle velocity 550 m/s (1,804 ft/s)
Effective range 14,500 m (15,857 yds)

The 21 cm Mörser 18 (heavy howitzer) (21 cm Mrs 18) was a German heavy howitzer used in the Second World War by independent artillery battalions and batteries. A number were also used by coast defense artillery units.

Design & History

A Mrs 18 on coastal defense duties in the Norwegian Arctic

The Mrs 18 was designed to replace the obsolescent World War I-era 21 cm Mrs 16. While the gun design itself was nothing innovative, the same cannot be said for the carriage. It was one of the first weapons, if not the first in quantity production, that used the interesting dual-recoil system. The barrel recoiled normally in its cradle, but, in addition, the whole top carriage, which carried the barrel and its cradle, recoiled across the main part of the carriage. This system damped out the recoil forces and made for a very steady firing platform. This carriage was also used for the 17 cm Kanone 18 in Mörserlafette and the 15 cm Schnelladekanone C/28 in Mörserlafette.

The Mrs 18 was an enormous weapon that was transported in two pieces, as was common for such large weapons. For travel the barrel was slid on to a separate trailer. The carriage carried an integral firing platform that was lowered to the ground when emplacing the howitzer. The wheels were then cranked up off the ground and it was now ready for firing. A rear castor-wheel jack was used to raise the rear spade off the ground if the gun needed to be traversed more than the 16° allowed by the mount proper.

The Mrs 18 entered production at a low rate in 1939 shortly before the war began. The Germans cancelled production in 1942 in lieu of its smaller brother, the 17 cm Kanone 18 in Mörserlafette, which could fire almost twice as far, but resumed production in 1943.[1]



  • Engelmann, Joachim and Scheibert, Horst. Deutsche Artillerie 1934–1945: Eine Dokumentation in Text, Skizzen und Bildern: Ausrüstung, Gliederung, Ausbildung, Führung, Einsatz. Limburg/Lahn, Germany: C. A. Starke, 1974
  • Hogg, Ian V. German Artillery of World War Two. 2nd corrected edition. Mechanicsville, PA: Stackpole Books, 1997 ISBN 1-85367-480-X

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