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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.
In Italy, Vickers Terni took over the construction under license of the 240 CT and 240 LT mortars, respectively named 'Bombarda da 240C' and 'Bombarda da 240L', adapted for use with cased propellant charges. But they also developed versions fitted with a muzzle extension assembled by a bolted sleeve, to extend the weapon's range. Thus appeared the :
- Bombarda da 240 CA, based on a 240 C whose barrel was lengthened by 1.5m,
- Bombarda da 240 LA, based on a 240 L whose barrel was extended by 1m,
- Bombarda da 240 LLA, based on a 240 L whose barrel was extended by 1.5m.
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Technical data :
- Complete description : Bombarda da 240 LA
- Design year : 1917
- Calibre : 240.00 mm
- Weight in firing position : Without platform : 1758 kg ('C') / 1818 kg ('L') / unknown ('LA' and 'LLA')
- Weight for transportation :
- Tube length in calibres : 0.00 Total length tube + breech : 1552 mm ('C') / 2450 mm ('L') / 2552 mm ('CA') / 3450 mm ('LA') / 4950 mm ('LLA')
- Grooves : 0 (smooth bore)
- Projectile weight : 67 kg
- Initial speed : unknown
- Fire rate : unknown
- Range : max 1200 m ('C') / 2500 m ('L') / 3800 m ('LA')
- Elevation range : +45 to +75 degrees ('C' and 'L') / +45 à +70 degrees ('LA')
- Direction range : 36 degrees total range
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(
Batignolles )