9.45 inch Heavy Mortar

Infobox Weapon
name= ML 9.45 inch Heavy Trench Mortar


caption=Australians loading a convert|9.45|in|mm|sing=on trench mortar, Battle of Pozières, France, August 2 1916.
origin=FRA
type= Heavy trench mortar
is_ranged=yes
is_bladed=
is_explosive=yes
is_artillery=yes
is_UK=yes
is_vehicle=
target=
date=
prod_date=
number=712 (UK)
service=1915 - 1918
used_by=UK
AUS
wars=World War I
designer=Dumezil-Batignolles
design_date=1915
manufacturer=
production_date=
weight=2,200 lb
length=
part_length=51 inch (Mk I)
69 inch (Mk II - IV)Handbook of the M.L. 9.45 inch Trench Mortars. February 1918. War Office, UK.]
crew=7
cartridge=HE 152 lb (UK)
caliber=240 mm (9.45 inch)
action=
rate=1 round every 6 minutes
velocity=475 ft/s (max charge)
range=660 - convert|2400|yd|abbr=on
max_range=
feed=
sights=
breech=
recoil=
weight=Mortar & elevating gear 499 lb, + body & bed 987 lb (Mk I)
644 lb, + 1169lb (Mk II - IV)
carriage=
elevation=75° - 45°
traverse=18° L & R
diameter=
filling=amatol or ammonal
filling_weight=
detonation=
yield=This large calibre mortar of World War I originated as a French design, the Mortier de 240 mm developed by Batignolles Company of Paris and introduced in 1915. Britain manufactured a modified version under license as the ML 9.45 inch Heavy Trench Mortar [ML being "muzzle loading"] , nicknamed the "Flying Pig" [The precise origin of the nickname "flying pig" is unclear. Some sources describe the bomb as looking like a small pig in flight; it may also refer to the English language term meaning an unlikely event (as in "pigs might fly"), deriving from the clumsy bulky appearance; it may be a mixture of both.] and it was the standard British heavy mortar from Autumn 1916 onwards.

History

The British ML convert|9.45|in|mm|sing=on mortar was a design based on the French 240 mm mortar in 1915 and introduced in 1916. The British version differed from the French LT weapon in that the propellant charge was loaded through the muzzle [ [http://cgsc.cdmhost.com/cdm4/item_viewer.php?CISOROOT=/p4013coll9&CISOPTR=133&CISOBOX=1&REC=2 "Manual for trench artillery, United States Army (provisional). Part I, Trench Artillery.". Prepared at Headquarters AEF, France, March 1918. page 8] ] whereas the French 240 mm had the charge loaded through the breech in a brass cartridge case.

In June 1916, following unsatisfactory trials with the French model, Britain replaced them with 30 of its own model, firing a 150 pound bomb, followed by 200 more in December 1916.General Sir Martin Farndale, "History of the Royal Regiment of Artillery. Western Front 1914-18". London: Royal Artillery Institution, 1986. Annex G, Trench Mortar Organization in France, page 367.]

The Mark I with convert|51|in|mm|sing=on barrel was introduced from June 1916. In 1917, the Mark II and Mark III followed with convert|69|in|mm|sing=on barrel, and small numbers of Mark IV.

Combat use

It was operated by crews of the Royal Garrison Artillery which was the part of the British Army that operated the heaviest artillery weapons, formed into batteries of 4 mortars attached to each division, designated "V/nn" where nn = division number. From February 1918 they were reorganised and moved from divisional to corps control.

The weapon was dismantled for transport, requiring 4 carts for the barrel, base, carriage and ammunition.

In action, a heavy timber platform was constructed embedded in the ground, on which the mortar base was immovably secured. The mortar carriage sat on the base and could traverse. The mortar barrel and breech were mounted on the carriage which provided elevation.

They were used in the "siege warfare" on the Western Front to destroy enemy strongpoints, bunkers and similar "hard" targets which were invulnerable to lighter mortars and field guns. The US Army handbook described it : "... the use for which it is primarily adapted is in the bombardment of strongly protected targets - dwellings, covered shelters, command posts, entrances to galleries, etc - or in the destruction of sectors of trenches, salients and the like." [http://cgsc.cdmhost.com/cdm4/item_viewer.php?CISOROOT=/p4013coll9&CISOPTR=137&CISOBOX=1&REC=3 "Handbook of the 9.45-inch trench mortar matériel" United States Ordnance Department. December 1917. page 9] ] . Their effectiveness decreased late in the war as German policy changed to a lightly held frontline, hence decreasing available targets, and they became redundant when the war of movement resumed late in 1918.

Both the propellant charge appropriate for the required range and the bomb were loaded via the muzzle. Usually a Lee-Enfield rifle's bolt action mechanism was screwed into the breech. A special blank rifle cartridge was loaded and was triggered by pulling a lanyard, and fired into an igniter at the base of the mortar chamber, igniting the propellant charge and launching the bombKevin Robert Keefe, [http://www.mortarsinminiature.com/British9.45inch.htm British convert|9.45|in|mm|sing=on Heavy Trench Mortar, Mark III] ] .

urviving Examples

*British 9.45 in mortar at Imperial War Museum London.

Notes

References

*"Handbook of the M.L. 9.45-In. Trench Mortars. Mks I, II and III." February 1918. War Office, UK. (Covers models in British service)

See also

*List of artillery#Heavy mortars
*240 mm Trench Mortar French, US & Italian version

External links

* [http://www.chakoten.dk/eng_skyttegravsmorter.html Om den engelske 9,45-tommers skyttegravsmorter Per Finsted,(in Danish)]
* [http://www.mortarsinminiature.com/British9.45inch.htm Kevin Robert Keefe, British 9.45in Heavy Trench Mortar, Mark III. with specifications and photographs of model]
* [http://www.1914-1918.net/trenchmortars.htm www.1914-1918.net The Trench Mortars Chris Baker]