David Porter on military history’s doomed inventions
The origins of what was officially the ‘Grenade, Hand, Anti-Tank No. 74’ go back to 1938, when Major Millis Jefferis began design studies for an anti-tank weapon based on what was later known as the ‘squash head’ principle.
Squash-head weapons are filled with plastic explosive and fitted with delayed-action base fuses. The plastic explosive is ‘squashed’ against the surface of the target tank on impact, and spreads out to form a disc or ‘pat’. The base fuse then detonates the explosive, creating a shock wave that blows lethal high-velocity fragments off the inner face of the armour. Some of the blast is also spread outwards – this is often powerful enough to blow off aerials and shatter gunsights.
The idea ‘took off’ in the aftermath of the Dunkirk evacuation, when a German invasion seemed imminent and there was a critical shortage of anti-tank weapons. At the time, Jefferis commanded MIR(c) – a secret department responsible for developing weapons for guerrilla warfare – and was able to get Churchill’s enthusiastic support for the sticky bomb.
The grenade, which went into production in late 1940, was a glass sphere containing approximately 1¼lb (0.57kg) of semiliquid desensitised nitroglycerine. The sphere was covered in stockinette, which was thickly coated with birdlime – a very strong adhesive.
A two-part casing of thin sheet-metal was then fitted around the sphere and held in place by a wooden handle containing a five-second fuse, together with two pins and a lever. The first pin was pulled out to make the casing fall away, and the second to arm the grenade, after which releasing the lever would initiate the fuse.
Dangerous to operate
Although the grenade could be thrown over short ranges, accuracy was poor and the recommended technique was to attach it to the target. The user would run up to the tank and smash the grenade on the engine decking, breaking the glass and spreading the nitroglycerine on to the hull in a thick paste.
He then had five seconds to get clear before the explosion, which could penetrate at least an inch (25mm) of armour – ample for smashing through the engine decks of most AFVs of 1940/1941.
In service, the sticky bomb’s problems rapidly became apparent. It could all too easily stick to the user’s equipment or uniform, leaving him struggling to pry the grenade loose while desperately holding on to the lever.
One member of the Home Guard recalled how a comrade ‘got his sticky bomb stuck to his trouser leg and couldn’t shift it. A quickthinking mate whipped the trousers off and got rid of them and the bomb. After the following explosion, the trousers were in a bit of a mess (though I think they were a bit of a mess prior to the explosion).’
It was also discovered that the nitroglycerine tended to become unstable in storage, which made the sticky bomb even more dangerous. Another hazard for users was the handle, which was shot away from the explosion ‘like a bullet.’
Despite all these problems, more than 2,500,000 sticky bombs were made before production ended in 1943.
This article was published in the August/September 2020 issue of Military History Matters. To find out more about the magazine and how to subscribe, click here.