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Mortier de 240 mm LT Mle 1916

Trench artillery

Contributor :
Bernard Plumier      http://www.passioncompassion1418.com
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Location :
Fleury devant Douaumont (55)
Coordinates : Lat : 49.19520 / Long : 5.43530
General comments on this surviving gun :

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

The head of one of these huge bombs points out the tube, and another one can be seen backwards, erected on its finned tail

Detailed view on the tube base with the vertical aiming mechanism and the breech drawer mechanism for insterting the 15° mm cartridges with the propulsive load

Historic and technical information
Denomination :     240 LT Mle 1916 Origin :       ( Batignolles)          

Historic context :

Appeared during the first quarter of 1915, the first reglementary French trench mortars of 58 mm Nr 1, 58 mm Nr 1 bis and 58 mm Nr 2 quick demonstrated their utility in close range vertical fire missions against entrenched troops, as well as for barbed wire network destruction or trenches devastation. But the finned tail projectiles that were launched by these weapons lacked the needed power to destroy deep dug-outs or particularly resistant defensive works, leaving the French army with no weapon comparable to the German heavy minenwerfer.

The French Head Quarters, via the Ordnance minister Albert Thomas and the General Dumézil, requested the development of a long range heavy trench mortar filling this gap 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 trrops. 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.

In the opposite camp, it inspired the Germans too with their 24 sm FlügelMinenWerfers IKO and Albrecht, as well as the Austrians (Böhler 24 cm Minenwerfer M16).

French even developped a version wity an incredible calibre of 340 mm ('mortier de 340 T' - 195 kg bomb !), but this latter weapon was rarely used and quickly abandoned, because of the way too important earthworks that were needed for its setup, including a narrow railway track for the ammo feeding.

Technical data :

  • Complete description : 240 mm Long Trench mortar M 1916 Dumézil-Batignolles
  • Design year : 1916
  • Calibre : 240.00 mm
  • Weight in firing position : 3600 kg incl. 2600 kg for the platform (1003 kg incl. 550 kg platform weight for the CT)
  • Weight for transportation :
  • Tube length in calibres : 0.00 2450 mm total length tube + breech (1552 mm for the CT)
  • Grooves : 0 (smooth bore)
  • Projectile weight : 81 à 85 kg (42 kg d'explosif)
  • Initial speed : 145 m/s (full prop. load)
  • Fire rate : 1 round each 6 minutes
  • Range : 2150 mm at full prop. load (1025 m for the CT)
  • Elevation range : 45 to 75 degrees
  • Direction range : 360 degrees range (CT and LT)

  • Les Crapouillots 1914-1918           Pierre Waline                   Charles Lavauzelle   1965  
  • Les canons de la Victoire 1914-1918 - Tome III - L' Artillerie de Côte et l'Artillerie de Tranchée       Général Guy François                   Histoire et Collection   2010  
  • Les Crapouillots 1914-1918       Général Rouquerol                   Payot   1935  
  • Cours d'Artillerie de Tranchée       Capitaine Bouchon                   Bourges   1918  
  • 240 et 340 T, les gros mortiers - Guerre, Blindés et Matériel Nr 117       Général Guy François                   Histoire et Collection   2016