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Mills bomb
N°5-MkII N°23-MkII N°36-MkI.jpg
Mills bombs. From left to right : N°5, N°23, N°36.
Type Hand grenade
Place of origin United Kingdom
Service history
In service 1915–1980s
Production history
Designed 1915
Number built 70 million +
Variants No. 5, No. 23,
No. 36, No. 36M
Weight 765 g (1 lb 11.0 oz)
Length 95.2mm
Diameter 61 mm (2.4 in)

Filling Baratol
7 seconds,
later reduced to 4

Mills bomb is the popular name for a series of prominent British hand grenades. They were the first modern fragmentation grenades in the world.[citation needed]


William Mills, a hand grenade designer from Sunderland, patented, developed and manufactured the "Mills bomb" at the Mills Munition Factory in Birmingham, England, in 1915.[1] The Mills bomb was inspired by an earlier design of the Belgian captain Leon Roland. Roland and Mills were later engaged a patent lawsuit.[2] The Mills bomb was adopted by the British Army as its standard hand grenade in 1915, and designated as the No. 5.[3] The Mills bomb underwent numerous modifications. The No. 23 was a variant of the No. 5 with a rodded base plug which allowed it to be fired from a rifle. This concept evolved further with the No. 36, a variant with a detachable base plate to allow use with a rifle discharger cup. The final variation of the Mills bomb, the No. 36M, was specially designed and waterproofed with shellac[3] for use initially in the hot climate of Mesopotamia in 1917, but remained in production for many years. By 1918 the No. 5 and No. 23 were declared obsolete and the No. 36 (but not the 36M) followed in 1932.

The Mills was a classic design; a grooved cast iron "pineapple" with a central striker held by a close hand lever and secured with a pin. According to Mills' notes the casing was grooved to make it easier to grip and not as an aid to fragmentation, and in practice it has been demonstrated that it does not shatter along the segmented lines. The Mills was a defensive grenade: after throwing the user had to take cover immediately. A competent thrower could manage 15 metres (49 feet) with reasonable accuracy, but the grenade could throw lethal fragments farther than this. The British Home Guard were instructed that throwing range of the No. 36 was about 30 yards with a danger area of about 100 yds.[4]

At first the grenade was fitted with a seven-second fuse, but during combat in the Battle of France in 1940 this delay proved too long—giving defenders time to escape the explosion, or even to throw the grenade back—and was reduced to four seconds.

The heavy, segmented bodies of "pineapple" type grenades result in an unpredictable pattern of fragmentation. After the Second World War Britain adopted grenades that contained segmented coiled wire in smooth metal casings. The No. 36M Mk.I remained the standard grenade of the British Armed Forces and was manufactured in the UK until 1972, when it was completely replaced by the L2 series. The 36M remained in service in some parts of the world such as India and Pakistan, where it was manufactured until the early 1980s. Mills bombs were still being used in combat as recently as 2004 e.g. the incident which killed US Marine Jason Dunham and wounded two of his comrades.[5]

The Mills bomb was also used by the Irish Republican Army.

Rifle grenade

The Mills bomb was developed into a rifle grenade by attaching a metallic rod to the base. This rod-type rifle-grenade has an effective range of about 150 yards. The operating procedure was to insert the Mills bomb rod down the barrel of a standard rifle, put a special blank cartridge in the rifle’s chamber, place the rifle stock on the ground, then pull the safety spoon on and immediately fire the rifle. If the soldier did not launch the grenade quickly, the grenade's fuze would run down and explode. It was found that the repeated launching of grenades by this method caused damage to a rifle’s barrel. This led to the development of a cup-type launcher to replace the rod-type rifle-grenade. This used a can shaped launcher was attached to the muzzle of the rifle and a gas check disc which screwed onto the base of the grenade. The gas check disc was screwed to the base of the grenade before the grenade was placed in the launcher. The safety pin could then be removed as the launcher cup kept the safety-spoon in place. The operator would then insert the blank cartridge into the rifle before setting the stock on the ground. When the cartridge was fired it pushed the grenade out of the cup releasing the spoon. The cup-type launcher could launch the grenade out to about 200 yards. Lee-Enfield rifles equipped with the cup launcher were modified with copper wire wrapped around the stock, to prevent the wood from cracking under the increased recoil. If necessary both the rod and the gas check grenade could be thrown as a standard hand-grenade.


See also


  1. U.S. Patent 1,178,092 U.S. copy of the 1915/1916 Mills grenade patent
  2. G. D. Sheffield (2007). War on the Western Front. Osprey Publishing. p. 196. ISBN 978-1-84603-210-3. 
  3. 3.0 3.1 " - Who's Who - Sir William Mills". 
  4. Capt. A. Southworth, M.B.E (1944)Home Guard Pocket Manual p47
  5. "Cpl Jason Dunham". Retrieved 23 October 2012. 

External links

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