2 inch Medium Mortar

Infobox Weapon
name= 2-inch Vickers Medium Trench Mortar
is_UK=yes


caption=British troops loading a 2 inch trench mortar with attached periscope post. Balkan front World War I.
is_artillery=yes
is_ranged=yes
is_bladed=
is_explosive=yes
is_vehicle=
type=Medium mortar
origin=flagcountry|United Kingdom
era=World War I
target=
date=1916
prod_date=
number=
service=1915 - 1917
used_by=British Empire
wars=World War I
designer=
design_date=
manufacturer=Vickers
production_date=
number=
part_length=36 inch (914mm) bore
40.85 inch (1,037mm) total
weight=
length=
crew=5 per mortar
25 per battery of 4 ["No. 351/38. Medium Trench Mortar Battery (Consisting of four mortars)". War Establishments, General, 1916. September 18, 1916.]
cartridge=HE 51 lb (23.13 kg) ["Appendix D. Details of Trench Mortars". 51 lb was the total projectile weight as fired, including filled bomb, fuze, and stick. The stick weighed about 8 lbs, the bomb about 42 lbs.]
Smoke
caliber= 2 inch (50.8 mm)
mortar barrel, not bomb
action=
rate=
velocity=
range=100 yds (91.4 m) min
570 yds (521.2 m) max
depending on charge
feed=
sights=
breech=
recoil=
weight=105 lbs (47.6 kg) ["Appendix D. Details of Trench Mortars". Mortar=105 lb; Bed=50 lb; Elevating Stand=50 lb; Tool Box=60 lb; Periscope box=70 lb; Temple silencer=47 lb; Rifle mechanism=5 lb; Total Weight for Transport = 497 lbs]
carriage=
elevation=
traverse=
diameter=
filling=Amatol or Ammonal
filling_weight=12.5 lb (5.6 kg) ["Appendix E. Details of Ammunition"]
detonation=
yield=The 2 inch Vickers Medium Trench Mortar, also known as the 2-inch Howitzer, and nicknamed the "Toffee Apple" or "Plum Pudding" mortar, was a British SBML medium trench mortar in use in World War I from late 1915 to early 1917. The designation "2 inch" refers to the mortar barrel, into which only the bomb shaft but not the bomb itself was inserted; the bomb itself was actually 9 inches in diameter and weighed 42 lbs, hence this weapon is more comparable to a standard mortar of approximately 4-inch bore.

History

Introduced late 1915.

Replaced by the Newton 6 inch Mortar from February 1917 onwards. Some Australian units retained them for projecting smoke screens.

Combat use

The weapon was initially operated by joint infantry and artillery detachments, eventually it became the responsibility of the Royal Field Artillery. [Clarke 2004, page 16] A typical infantry division was equipped with 3 batteries designated X, Y, Z, each with 4 mortars.

It fired a spherical cast-iron bomb "the size of a football" [Pratt 1965] painted dirty white filled with Amatol (identified by a painted green band) or Ammonal (identified by a painted pink band) attached to the end of a pipe ("stick"), hence the nicknames "Toffee Apple" and "Plum Pudding". Weights of bombs as delivered without fuzes varied. Light bombs, from 39 lb 14 oz to below 40 lb 10 oz, were marked with a stencilled "L". Heavy bombs, above 41 lb 10 oz to 42 lb 6 oz were marked with a stencilled "Hv".Handbook of the M.L. 2-Inch Trench Mortar, Mark I. 1917, page 13] Hence the total fuzed weight with stick of 51 lb is only an average.

2-inch refers to the mortar barrel's bore and the projectile stick inserted into it, not the much-larger bomb itself which remained outside the barrel. It was comparable in explosive power if not range to other 4-inch mortars.

Its primary use was in cutting barbed wire defensesRuffell] and attacking enemy front line trenches, such as in the July 1916 attack on the Somme [Pratt 1965] . The spherical shape and relatively low velocity brought the benefit that the bomb did not penetrate the ground before exploding. The short range was a disadvantage as it could only be used if no man's land (between the British and enemy front line) was relatively narrow. It was used to fire some White Star (50%-50% Chlorine and Phosgene) gas bombs during the Battle of the Somme [Jones 2007, page 27] but only as a stopgap measure until other specialised longer range projectors became available.

Cordite charges appropriate to the required range were dropped into the barrel before the bomb was loaded. Charges and ranges:-
*1.5 ounces : 100 - 220 yards (dangerous due to propensity for incomplete burn and hence to fall short)
*2.5 ounces : 180 - 340 yards
*3.5 ounces : 300 - 500 yards

A Lee-Enfield bolt mechanism and chamber was screwed into a socket in the top of the barrel near the base.Handbook of the M.L. 2-Inch Trench Mortar. Mark I. 1917, page 1] A special blank rifle cartridge was loaded and fired via a long lanyard from a sheltered position if possible due to the risk of bombs falling short. This ignited the propellant charge and launched the bomb.

In early use it was situated in frontline trenches but this tended to attract enemy fire onto the troops manning them. Standard procedure became to locate the mortars separately from frontline trenches, in unoccupied trenches or in saps running off the frontline. This had the benefit of drawing enemy fire away from troops manning the front line [Pratt 1965] .

Estimated rounds required for various targets, with instantaneous percussion fuze 107 : [Artillery in Offensive Operations, January 1917]
*Cutting barbed wire : 1 round per 10 sq. yards
*Cutting loose wire : 1 round per 6 sq. yards
*Destroy trenches frontally : 5 rounds per yard
*Destroy trenches in enfilade : 2.5 rounds per yard
*Destroy a machine-gun emplacement with top cover not more than 3 feet of earth : 80 rounds

Provision was made for attachment of the "Temple Silencer" at the muzzle,Handbook of the M.L. 2-Inch Trench Mortar. Mark I. 1917, page 1] but it is unknown whether this was used in combat.

Use as anti-tank mines

In Spring 1918 many of the by-then obsolescent bombs were buried on the Western Front under metal plates as anti-tank mines in expectation of attack by German tanks. This led to some later confusion as to whether unearthed bombs were unexploded mortar projectiles ("Duds") or undetonated mines.

These minefields were inadequately documented. This caused the British problems in the closing months of the war when they had to advance again over territory they had previously abandoned, and also prevented full clearance of the minefields after the war. This led to some French farmers being blown up in the 1930s when they started using tractors e.g. around Gouzeaucourt.

See also

*Mortar
*Mortier de 58 mm type 2
*List of artillery#Mortars

urviving examples

Image Gallery

Notes

References

*Handbook of the M.L. 2-inch trench mortar, Mark I: land service. War Office, United Kingdom, 1917.
* [http://cgsc.cdmhost.com/u?/p4013coll9,89 Appendix D. Details of Trench Mortars. in Field Artillery Notes No. 7. US Army War College August 1917.] Provided online by Combined Arms Research Library
* [http://cgsc.cdmhost.com/u?/p4013coll9,89 Appendix E. Details of Ammunition. in Field Artillery Notes No. 7. US Army War College August 1917.] Provided online by Combined Arms Research Library
* [http://cgsc.cdmhost.com/u?/p4013coll9,86 "Artillery in Offensive Operations" GHQ Artillery Notes No. 4 January/February 1917. Redistributed by US Army War College August 1917.] Provided online by Combined Arms Research Library
*Dale Clarke, [http://www.ospreypublishing.com/title_detail.php/title=S6887 British Artillery 1914-1919. Field Army Artillery. Osprey Publishing, Oxford UK, 2004]
*Simon Jones, [http://www.ospreypublishing.com/title_detail.php/title=T1516 World War I Gas Warfare Tactics and Equipment. Osprey Publishing, Oxford, 2007]
*Lt. Colonel E.R. Pratt O.B.E. M.C., [http://www.hellfire-corner.demon.co.uk/fuse.htm "The Origin of a Fuse", 1965.]
*WL Ruffell, [http://riv.co.nz/rnza/hist/mortar/mort14.htm The 2-inch Howitzer]

External links