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Great Britain

M.L. 9.45-in. trench mortar 'Flying Pig' Mk I, Mk II and Mk III

Mk I

Trench artillery

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Location :
Longueval (80)
Monument aux Morts
Coordinates : Lat : 50.02610 / Long : 2.80390
General comments on this surviving gun :

Identical items in the same location : 1
Items covered by this file : 1

The base in in poor condition, but the solid breech pierced by the firing hole allows to identifiy this mortar as a British 9.45 and not a French 240

Front view, the short barrel means this mortar is an initial Mk I version

Historic and technical information
Denomination :     9.45-in. trench mortar 'Flying Pig' Origin :       ( Inconnu)             ( Batignolles )          

Historic context :

The French Head Quarters, via the Ordnance minister Albert Thomas and the General Dumézil, requested the development of a long range heavy trench mortar by the company 'Société des Batignolles'. Ordered in July 1915, the first 'mortiers de 240 CT' ('CT' pour 'Court de Tranchées') made a brilliant start in specialised units during the same year September 25th Champagne offensive. This heavy weapon (1003 kg including 550 kg for the heavy wooden platform) compensated the lack of mobility due to its ig weight by a nice range that allowed it to stay behind the first lines. The frightening effects of its 87 kg 'M' bomb (including 47 kg explosive) that was propulsed at a distance of 1025 m (then 1440 m for the 83 kg 'T' bomb with 42 kg explosive) caused terror and devastation in the German trenches.

The 240 CT mortar production was stopped in 1916 after 182 pieces only (100 in 1915 and 82 in 1916), immediately leaving the place to the new elongated version 'mortier de 240 LT' ('LT' for 'Long de Tranchées') that improved a lot the range, the ballistic properties and the reliability of the weapon. This mortar survived to the Great War was launching finned tail bombs of 85 kg (incl. 42 kg explosive) at a distance more than 2 km.

The finned tail bomb was entirely inserted inside the tube by its mouth, the propulsive charge being located inside a 150 mm CTR gun used cartridge loaded by the drawer mechanism of the breech. This weapon setup was long and difficult, and the particularly heavy weight the (2600 kg !!) of the materials (steel and wood) needed for building the platform limited its mobility. Weighting more than 3.5 tons, it came in operation in July 1916 and was massively and successfully used during the Somme offensive.

The mortier de 240 LT was built in 477 items (64 finished only after the end of the war). It was adopted without changes by the US and Italian troops.

The concept was kept and used afterwards by the British army (giving birth to the 9.45 inches heavy trench mortar 'Flying Pig'), after long tests and some changes, including the replacement of the drawer type breech for the use of cartridge conditionned propulsive charge by a solid breech with a lighting hole for the use of a propulsive charge introduced by the muzzle.

Four successive versions were built :

  • the Mk I with a short tube equivalent to the French 240 CT, built in 203 items from June 1916,
  • the Mk II with an elongated tube comparable to the French 240 LT, built in 336 items from 1917,
  • the Mk III built in 162 items,
  • the Mk IV built in 11 items.

Technical data :

  • Complete description : 9.45 inches trench mortar 'Flying Pig' Mk I, II and III
  • Design year : 1916
  • Calibre : 240.00 mm
  • Weight in firing position : 1486 lb (674 kg) for Mk I, 1843 (836 kg) for the Mk II, III and IV
  • Weight for transportation :
  • Tube length in calibres : 0.00 1295 mm (51 in) for the Mk I, 1752 mm (69 in) for the Mk II, III and IV
  • Grooves : 0 (smooth bore)
  • Projectile weight : 69 kg
  • Initial speed : 145 m/s at full load
  • Fire rate : 1 shot per 6 minutes
  • Range : 600 m to 2190 m
  • Elevation range : +45 to +75 degrees
  • Direction range : 36 degrees total range

  • Allied Artillery of World War One           Ian V. Hogg                   Crowood   1998  
  • Weapons of the Trench War 1914-1918       Anthony Saunders                   Sutton   1999