WW1 2-Inch Trench Mortar

The British Army entered the First World War with very few mortars, and certainly none at the battalion level. As the stalemate of trench warfare set in and the effectiveness of enemy mortars became clear it was decided that trench mortars of various sizes would be needed.

Nicknamed ‘plum pudding’ or ‘toffee apple’ mortars after their projectile’s characteristic shape, the 2 inch Medium Mortar or 2 inch Trench Howitzer, was one of Britain’s first effective light trench mortars to be introduced.

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Right-side view of the 2in Trench Mortar (Matthew Moss)

Trench mortars were the army’s most forward artillery, right up on the front line. These short range weapons were able to throw large, high explosive projectiles, short distances across No Man’s Land at the enemy trench system opposite. The 2 inch mortar was considered accurate out to 350 yards with a maximum effective range out to just under 600 yards.

Introduced in 1915, the 2 inch mortar was originally crewed by men taken from the battalion it was stationed with, along with some specialists from the Royal Artillery. However, with the introduction of the 3 inch Stokes mortar which was operated by the infantry themselves the 2 inch mortars became the sole responsibility of the Royal Field Artillery.

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A young gunner loads a 2in spigot mortar bomb into his mortar (Imperial War Museum)

Mortar positions were often in secondary trenches just behind the infantry’s frontline. This was to help protect the infantry from potential counter-battery fire. The trench mortars were often deployed to sectors to provide counter battery fire against German minenwerfers or in the run up to an offensive or local action. A British Army report on artillery use, drawn up in February 1917, noted that “Owing to their liability to be destroyed by hostile artillery fire it may often be advisable to defer opening fire with these mortars till the last day of bombardment.” The mortars were also tasked with keeping gaps made in the wire clear and with supporting any feint attacks made by infantry during gaps in the bombardment running up to a larger offensive.

Llewelyn Wyn Griffith, a captain with the 15th Royal Welch Fusiliers and later a novelist, recalled in his war memoir:

“At night a trench mortar officer set his guns in a derelict trench about twenty yards behind the line and carried up his ammunition, heavy globes of iron with a little cylindrical projection like a broken handle. In the morning I moved the men from the bays between the trench mortars and their target, to lighten the risk of loss from retaliatory fire.”

Sometimes the width of No Man’s Land required saps to be cut extending out from the frontline so the mortar rounds didn’t fall short. The 50 lb lollipop-like projectile had a maximum effective range of 570 yards (depending on the size of cordite charge used), and could create a crater 5 feet deep and 14 feet wide. The ideal mortar position was a 6 feet wide by 9 feet deep sandbagged pit with the weapon’s heavy wooden bed at the bottom and room for the crew to load the mortar.

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A British 2in Mortar position in Mesopotamia, note the ignitor’s breech is open (Imperial War Museum)

Crews could manage to fire approximately once every two minutes. Much slower than the lighter 3 inch Stokes Mortar and but faster than the heavy 9.45 inch Heavy Mortar. The mortar comprising of just its tube, bed, stand and ignition system weighed 320 lbs (145kg), not including the accompanying tools and the Temple silencer system which could be fitted (which weighed 47 lbs or 21 kg alone).

Typically manned by a 5 man mortar crew comprising of an NCO, gunners, and ammunition bearers. To operate the 2 inch mortar a cordite charge was first placed down the tube, the projectile’s shaft was then inserted on top of the charge, the projectile’s fuse was set and checked and a new blank cartridge chambered in the ignition system. The crew then got clear of the weapon and pulled the lanyard to fire the mortar. To reload the crew ran a clearing stick down the tube and then repeated the loading process.

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The business end, a view down the length of the mortar (Matthew Moss)

Interestingly, the 2 inch Medium Mortar, like the larger 9.45 inch Heavy Mortar used a cut-down rifle, which screwed into the ‘breech’ end of the mortar tube. This particular mortar has an 1894-dated cut down Lee-Enfield MkI as its ignition system, the cutdown rifle has a wooden insert in its magazine well but it still has its rear volley sight attached. This reusable system replaced the T-tube Friction ignitor, which was in high demand by Britain’s bigger guns. The Lee-Enfield-based system enabled the cordite propellant charges to be ignited by a blank .303 round instead. The rifle’s trigger was pulled with a lanyard from nearby cover. These cutdown ignitor rifle are sometimes confused for Obrez-style Lee-Enfields.

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A close up look at the 2in Mortar’s SMLE ignitor (Matthew Moss)

The weight of the cordite charge used dictated the range while a variety of different fuses were used with the projectiles, these screwed into the nose of the bomb. The sphere was about 9.3 inches in diameter with a 2 inch thread for the fuse at its head and a cup for the 22 inch long, 2 inch thick solid cast iron stick or spigot at its base. The sphere was filled with high explosive (Amatol or Ammonal). The high explosive bombs were painted white with a green or pink stripe around their middle.

They were often deployed in batteries of four with three Royal Field Artillery medium mortar batteries attached to each division. The mortars were predominantly tasked with cutting enemy barbed wire and destroying enemy trenches and forward positions, such a machine gun nests.

Royal Army Ordnance Corps playing cards 1916
Men of the Royal Army Ordnance Corps playing cards on a dump of trench mortar ammunition during Battle of the Somme (Imperial War Museum)

Captain Griffith described a battery of 2 inch mortars opening fire on enemy lines:

“A pop, and then a black ball went soaring up, spinning round as it went through the air slowly; more pops and more queer birds against the sky. A stutter of terrific detonations seems to shake the air and the ground, sandbags and bits of timber sailed up slowly and then fell in a calm deliberate way. In the silence that followed the explosions, an angry voice called out in English across No Man’s Land, ‘YOU BLOODY WELSH MURDERERS.’

The 2 inch medium mortar entered service in spring 1915 and remained in use into 1917 with British and Empire troops. It was used on the Western Front and in Mesopotamia. Over 800 were ordered initially with 675,000 bombs, many of the mortars were made in railway and agricultural machinery workshops, allowing larger factories to focus on more complex weapons. The 2 inch mortar was superseded by the larger bore Newton 6 inch mortar later in the war. Some of the remaining 2 inch projectiles were re-purposed as makeshift anti-tank mines, buried in no man’s land in anticipation of possible German tank attacks.

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Specifications:

Barrel Length: 3 feet (90cm)
Overall Weight: ~340lbs (154kg)
Projectile Types: High explosive & smoke
Projectile Weight: 51lbs (23kg)
Effective Range: 100-570 yards (90-520m)


Bibliography:

Primary Sources:

Field Artillery Notes No.7, US Army War College, (1917) (source)

‘Artillery in Offensive Operations’ GHQ Artillery Notes No. 4 January/February 1917 (source)

‘History of the Ministry of Munitions’, Volume XI, Part I Trench Warfare Supplies (1922)

Up to Mametz, L.W. Griffith,  (1931)

Newsreels:

The Battle of the Somme, 1916, Imperial War Museum (source)

With the Forces in Mesopotamia, 1917, Imperial War Museum (source)

Secondary Sources:

British Artillery 1914-1919. Field Army Artillery, D. Clarke, (2004)

Tommy, R. Holmes, (2004)

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