| 3 inch Stokes mortar | |
|---|---|
 SirWilfred Stokes with example of his mortar and bombs. Typical 3-inch bombs used are 2nd and 6th from left | |
| Type | Light mortar |
| Place of origin | United Kingdom |
| Service history | |
| Used by | |
| Wars | |
| Production history | |
| Designer | Sir Wilfred StokesKBE |
| Designed | 1915 |
| Specifications | |
| Mass | 104 lb (47.2 kg) total[3] |
| Crew | 2 |
| Shell | HE 10 lb 11 oz (4.85 kg)[4] |
| Calibre | 3.2 in (81 mm)[5] |
| Action | Trip |
| Elevation | 45–75°[6] |
| Rate of fire | 25 rpm (maximum)[7] 6–8 rpm (sustained) |
| Effective firing range | 750 yd (686 m) |
| Maximum firing range | 800 yd (732 m)[8] |
| Filling | Amatol |
| Filling weight | 2 lb 4 oz (1 kg)[9] |
TheStokes mortar was a Britishtrench mortar designed bySir Wilfred StokesKBE that was issued to theBritish andU.S. armies, as well as thePortuguese Expeditionary Corps, during the latter half of theFirst World War. The 3-inch trench mortar is a smooth-bore, muzzle-loading weapon for high angles of fire. Although it is called a 3-inch mortar, its bore is actually 3.2 inches or 81 mm.[5]
The Stokes mortar was a simple weapon, consisting of asmoothbore metal tube fixed to a base plate (to absorb recoil) with a lightweightbipod mount. When a mortar bomb was dropped into the tube, an impact sensitiveprimer in the base of the bomb would make contact with a firing pin at the base of the tube, and ignite the propellant charge in the base, launching the bomb towards the target. The warhead itself was detonated by an impact fuse on reaching the target.
The barrel is a seamless drawn-steel tube necked down at the breech or base end. To the breech end is fitted a base cap, within which is secured a firing pin protruding into the barrel. The caps at each end of the bomb cylinder were 81 mm diameter. The bomb was fitted with a modifiedhand grenadefuse on the front, with a perforated tube containing a propellant charge and an impact-sensitive cap at the rear.
Range was determined by the amount of propellant charge used and the angle of the barrel. A basic propellant cartridge was used for all firing, and covered short ranges. Up to four additional "rings" of propellant were used for incrementally greater ranges. The four rings were supplied with the cartridge and gunners discarded the rings that were not needed.
One potential problem was the recoil, which was "exceptionally severe, because the barrel is only about 3 times the weight of the projectile, instead of about one hundred times the weight as in artillery. Unless the legs are properly set up they are liable to injury".[10]
A modified version of the mortar, which fired a modern fin-stabilised streamlined projectile and had a booster charge for longer range, was developed after World War I;[11] this was in effect a new weapon.
Light mortars portable by one man had already been in use centuries earlier, but had fallen out of general usage since theNapoleonic era. With the many changes to battlefield doctrine during the First World War, the concept gained interest again. At first the British and French resorted to re-issuing these obsolete mortars;[12] after modernised designs became available, the Stokes mortar in particular gained popularity.
Frederick Wilfred Scott Stokes – who later became Sir Wilfred Stokes KBE – designed the mortar in January 1915. The British Army was at the time trying to develop a weapon that would be a match for theImperial German Army'sMinenwerfer mortar, which was in use on theWestern Front.
Stokes's design was initially rejected in June 1915 because it was unable to use existing stocks of British mortar ammunition. It took the intervention ofDavid Lloyd George (at that timeMinister of Munitions) and Lieutenant-Colonel J. C. Matheson of the Trench Warfare Supply Department (who reported to Lloyd George) to expedite manufacture of the Stokes mortar.
In the last quarter of 1915, 304 Stokes mortars were produced. Only 104 of these reached the front, however, the remainder being sent to training schools.[13] The subcontracting-out of manufacture of the mortar mounting was undertaken in February 1916.[14] In March 1916, it was announced the light trench mortars would be controlled by Infantry Brigades. The handbook for the Stokes trench mortar was issued to the infantry in April 1916.[15] In total, 11,331 3-inch Stokes mortars were manufactured in Britain.[16]
It remained in service into the Second World War, when it was superseded by theOrdnance ML 3 inch mortar, and some remained in use by New Zealand forces until after theSecond World War.
Stokes received aknighthood[17] for inventing the modern mortar, and was given several forms of monetary reward by theMinistry of Munitions.[citation needed]
The French developed an improved version of the Stokes mortar as theBrandt Mle 27, further refined as theBrandt Mle 31; this design was widely copied with and without licence.[18][19] Despite their indigenous production, out of 8,000 81 mm mortars in service with the French in 1939, 2,000 were of the original Mk. I build purchased from Great Britain.[20]
In World War I, the Stokes mortar could fire as many as 25 bombs per minute and had a maximum range of 800 yards (732 m) firing the original cylindrical un-stabilised projectile. British Empire units had 1,636 Stokes mortars in service on theWestern Front at the Armistice.[21]
AfterAmerican entry into World War I, the Stokes mortar was standardised as the "Mortar, Trench, 3", Mk. I" and "Mortar, Trench, 3", Mk. IA2." Although production of the weapon was started in the United States before the end of the war, few American-built weapons reached France and most of those actually used in combat were of British manufacture. It was used in theBanana Wars and helped American forces defeatSandinista rebels during theSecond Battle of Las Cruces on 1 January 1928.[22] Refinements of the British Stokes mortar were made by French weapons designerEdgar Brandt in theinterwar period, resulting in theBrandt mortar. The new weapon, which was adopted by the Americans as theM1 mortar and put into limited production starting in 1935, had a heavier barrel, cross-leveling device on the bipod, and a new base plate. By 1942, the Mk. I and Mk. IA2 had been fully supplanted by the M1 and reclassified as "limited standard."[5]
TheParaguayan Army made extensive use of the Stokes mortar during theChaco War, especially as asiege weapon in theBattle of Boquerón in September 1932.[1][2] Stokes mortars were widely used by theRepublican Army during theSpanish Civil War,sold mostly by Poland. In September 1936, 44,000 Stokes rounds arrived in Spain.[23]
A 4-inch (102 mm) calibre version of the Stokes design was used to fire smoke, poison gas, andthermite (incendiary) rounds. A quantity of just under thirty were first used at the Battle of Loos in September 1915.[12] Up to the end of 1918, a total of 1,123 were manufactured.[24] This weapon, used solely by the Special Brigade of theRoyal Engineers,[25] should be considered a separate weapon from the standard "3-inch" 81-millimetre (3 in) version used by the infantry.[26]
{{cite web}}: CS1 maint: url-status (link)Forty ancientCoehorn mortars, firing spherical ammunition using black powder charges,were obtained from the French, and were actually fired at the battles at Neuve Chapelle and Aubers Ridge.
{{cite report}}: CS1 maint: numeric names: authors list (link)
