The No. 73 grenade, also known as the "Thermos", "Woolworth bomb",[2] or "hand percussion grenade",[3] was a British anti-tank grenade used during the Second World War. It got its nickname from the resemblance to a Thermos flask.
With the end of the Battle of France and the evacuation of the British Expeditionary Force from the port of Dunkirk between 26 May and 4 June 1940, a German invasion of Great Britain seemed likely.[4] The British Army was not well-equipped to defend the country in such an event; in the weeks after the Dunkirk evacuation it could only field twenty-seven divisions.[5] The Army was particularly short of anti-tank guns, 840 of which had been left behind in France leaving only 167 available in Britain; ammunition was so scarce for the remaining guns that regulations forbade any being used for training purposes.[5]
As a result of these shortcomings, new anti-tank weapons had to be developed to equip the British Army and the Home Guard with the means to repel German armoured vehicles.[6] Many of these were anti-tankhand grenades, large numbers of which could be built in a very short space of time and for a low cost.[2] They included the grenade, hand, anti-tank No. 74, also known as the "sticky bomb", which was coated with a strong adhesive and stuck to a vehicle, and the No. 76 special incendiary grenade, essentially a simple white phosphorusincendiary contained in a breakable glass container, like a more sophisticated variation of the Molotov cocktail (which simply uses a flammable liquid such as gasoline and a burning rag as a "fuse").[7] Ian Hogg states that the simplest of these grenades was the No. 73 grenade.
The No. 73 grenade had a roughly cylindrical shape and plastic screw-on cap,[8] similar to that of a Thermos flask, from which the "Thermos bomb" nickname was derived.[9] It was approximately 3.5 inches (89 mm) in diameter and 11 inches (280 mm) in length,[10] and weighed 4.5 pounds (2.0 kg). Its explosive content consisted of 3.5 pounds (1.6 kg) of polar ammonal gelatine dynamite or nitrogelatine – both of which were highly flammable and could be detonated by the impact of small-arms fire.[8] When thrown at a tank or other vehicle, a weighted tape held in the users hand unravelled and pulled free a safety pin, which was attached to a Type 247 "all-ways" fuze (the same type used in the Gammon bomb and No. 69 grenade); this armed and then detonated the grenade.[11] Its weight meant that it could only be thrown short distances,[2] limiting its range to between 10 and 15 yards (9 and 14 m),[8] and its detonation could injure the user if they did not find cover before it detonated.[2] It was able to penetrate 2 inches (51 mm) of armour,[12] and "damage severely any light tank."[3] It was best used against the tracks of a tank, which it could easily blow off[8] and force its crew to waste time by stopping and repairing it.[13]
The No. 73 grenade was first issued in the last months of 1940, but it was rarely used as an anti-tank grenade; instead the fuze was usually removed and it was used as a demolition charge. It was withdrawn from service within a year, and reissued again in 1943 for the express purpose of being used for demolition work.[8] On 27 May 1942, a modified version of the grenade was used in the assassination of SS-Obergruppenführer Reinhard Heydrich, when paratrooper Jan Kubiš threw it at Heydrich's car in Prague. The bomb used for this purpose had been shortened.[14]
Bull, Stephen; Dennis, Peter; Delf, Brian; Chappell, Mike; Windrow, Martin (2004). World War II Infantry Tactics. Osprey Publishing. ISBN1-84176-663-1.
Hogg, Ian (1995). Tank Killers: Anti-Tank Warfare by Men and Machines. Pan Macmillan. ISBN0-330-35316-0.
Lampe, David (1968). The Last Ditch: Britain's Secret Resistance and the Nazi Invasion Plan. Greenhill Books. ISBN978-1-85367-730-4.
Longmate, Norman (1974). The Real Dad's Army: The Story of the Home Guard. Hutchinson Library Services.
Lowry, Bernard; Taylor, Chris; Boulanger, Vincent (2004). British Home Defences 1940–45. Osprey Publishing. ISBN1-84176-767-0.
Mackenzie, S.P. (1995). The Home Guard: A Military and Political History. Oxford University Press. ISBN0-19-820577-5.
Rottman, Gordon L.; Noon, Steve; Windrow, Martin (2005). World War II Infantry Anti-Tank Tactics. Osprey Publishing. ISBN1-84176-842-1.
Rottman, Gordon L.; Dennis, Peter (2008). World War II Infantry Assault Tactics. Osprey Publishing. ISBN978-1-84603-191-5.
The Hand Percussion Grenade (Anti-tank No. 73, Mark I). Tank Hunting and Destruction, Military Training Manual No 42, Appendix D. War Office. February 1941.
