| Newton 6-inch mortar | |
|---|---|
 Canadian troops firing the 6-inch (152.4 mm) mortar in the open atValenciennes in 1918 | |
| Type | Medium mortar |
| Place of origin | United Kingdom |
| Service history | |
| In service | 1917–1918 |
| Used by | British Empire United States |
| Wars | World War I |
| Production history | |
| Designer | Captain H Newton, 5th BtnSherwood Foresters |
| Designed | 1916 |
| No. built | UK : 2,538[1] |
| Specifications | |
| Barrel length | Bore: 4 ft 6 in (1.37 m) Total: 4 ft 9 in (1.45 m)[2] |
| Shell | HE 52 lb (24 kg)[3] |
| Calibre | 6 inches (152.4 mm) |
| Elevation | 77°–45° |
| Rate of fire | 8 rounds/min[4] |
| Effective firing range | 100 - 1,420 yds (91 - 1,298 m) |
| Maximum firing range | 1,950 yd (1,780 m)[5] |
| Filling | Amatol,Ammonal or Sabulite |
| Filling weight | 22 pounds (9.98 kg) |
TheNewton 6-inch mortar was the standard British mediummortar inWorld War I from early 1917 onwards.
The Newton 6-inch replaced the2-inch medium mortar beginning in February 1917.
It was a simple smooth bore muzzle-loading mortar consisting of a 57-inch (1,448 mm) one-piece steel tube barrel, with a "striker stud" inside the centre of the closed base of the tube. The rounded external base of the tube sat in a socket in the flat cast steel base, which in turn sat on a wooden platform. An "elevating guy" (cable) connected to a loop in the upper side of the barrel and the rear end of the bed. "Traversing guys" (cables) connected to loops on each side of the barrel and eyebolts on the upper sides of the bed. Hence aiming of the barrel was done by adjusting the length of the guys via adjusting screws. A socket in the barrel base allowed for emergency firing via a "misfire plug" in the case of misfires (i.e. if the bomb remained in the barrel due to failure of the propellant to ignite).[6]
British Empire divisions were initially equipped with three batteries of four mortars designatedX,Y andZ. From February 1918 onwards, these were consolidated into two batteries,X andY, of six mortars each, andZ was dissolved. In British use, they were operated by theRoyal Field Artillery and formed part of thedivisional artillery, with one battery attached to each of the divisional artillerybrigades.
The United States Army began production and equipping with this mortar late in the war but it is doubtful whether any were used in combat.
The mortar was operated from concealed pits close to the front line duringtrench warfare, and was used in the open during the final "mobile warfare" phase of the First World War, depending on available transport. The disassembled weapon was usually transported on horsedrawn carts but theCanadian Automobile Machine Gun Brigade (the Canadian Independent Force or "Brutinel's Brigade") is known to have successfully used the mortar both mounted on motor trucks and dismounted in the closing months of the war.[7][8]
The 52-pound cast-iron fin-stabilised high explosive bomb carried the percussion primer at the base in the intersection of the four vanes (fins), consisting of a specially loaded blank .303 rifle cartridge. The basic propellant charges were contained in four small white cambric bags each containing 1 oz ofguncotton yarn. These were held in place in the four angles between the bomb's fins. For ranges less than 1000 yards, one or more bags could be removed, as per range tables.
For ranges above 1,000 yards (910 m), additional charges were loaded before the bomb, held in two white cambric bags each containing 1 oz 4 drm ofcordite.[9]
In action the gunners would adjust the angle of the barrel via the elevating guy (for distance) and traversing guys (for direction). The manual warns: "See that the elevating and traversing screws of the guys are always tight. A slack guy leads to inaccurate shooting, and the stresses on firing are not equally distributed; this is usually the cause of the guys breaking".[10]
The range tables specified the barrel angle and propellant charges required. The additional cordite propelling charge bags were dropped down the barrel if necessary, or necessary number of propellant charges removed from the bomb, and the bomb's fuze was set. The gunners stood back, the bomb was dropped down the barrel, the detonator in the base of the .303 cartridge in the base of the bomb struck a pin in the bottom of the barrel and fired, igniting the guncotton charges in the base of the bomb, which in turn ignited thecordite charges if present. The resulting rapid gas expansion propelled the bomb up the barrel and to its target.
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