Editing PIAT (section)

==Development==
At the beginning of the Second World War, the British Army possessed two primary anti-tank weapons for its infantry: the [[Boys anti-tank rifle]]<ref>Khan, p. 1</ref> and the [[No. 68 AT grenade|No. 68 AT rifle grenade]].<ref name="Khan2">Khan, p. 2</ref> However, neither of these was particularly effective as an anti-tank weapon. The No. 68 anti-tank grenade was designed to be fired from a discharger fitted onto the muzzle of an infantryman's rifle, but this meant that the grenade was too light to deal significant damage, resulting in it rarely being used in action.<ref name=Weeks>Weeks, p. 84</ref> The Boys was also inadequate in the anti-tank role. It was heavy, which meant that it was difficult for infantry to handle effectively, and was outdated; by 1940 it was effective only at short ranges, and then only against [[Armored car (military)|armoured cars]] and [[light tank]]s. In November 1941 during [[Operation Crusader]], part of the [[North African Campaign]], staff officers of the [[Eighth Army (United Kingdom)|British Eighth Army]] were unable to find even a single instance of a Boys knocking out a German tank.<ref name="French">French, pp. 88–89</ref>

Due to these limits, a new infantry anti-tank weapon was required, and this ultimately came in the form of the Projector, Infantry, Anti-Tank, commonly abbreviated to PIAT. The origins of the PIAT can be traced back as far as 1888, when an American engineer by the name of [[Charles Edward Munroe]] was experimenting with [[guncotton]]; he discovered that the explosive would yield a great deal more damage if there were a recess in it facing the target. This phenomenon is known as the "[[Munroe effect]]". The German scientist Egon Neumann found that lining the recess with metal enhanced the damage dealt even more.<ref name="Khan2"/> By the 1930s [[Henry Mohaupt]], a Swiss engineer, had developed this technology even further and created shaped charge ammunition. This consisted of a recessed metal cone placed into an explosive warhead; when the warhead hit its target, the explosive detonated and turned the cone into an extremely high-speed spike. The speed of the spike, and the immense pressure it caused on impact allowed it to create a small hole in armour plating and send a large pressure wave and large amounts of fragments into the interior of the target. It was this technology that was used in the No. 68 AT grenade.<ref name="Khan2"/>

[[File:PIAT AT-SPG CDN WWII.jpg|thumb|PIAT and ammunition case at the [[Canadian War Museum]]]]

Although the technology existed, it remained for British designers to develop a system that could deliver shaped charge ammunition in a larger size and with a greater range than that possessed by the No. 68. At the same time that Mohaupt was developing shaped charge ammunition, [[Lieutenant Colonel]] [[Stewart Blacker]] of the [[Royal Artillery]] was investigating the possibility of developing a lightweight [[platoon]] [[Mortar (weapon)|mortar]].<ref name="Hogg42">Hogg, p. 42</ref> However, rather than using the conventional system of firing the mortar shell from a barrel fixed to a baseplate, Blacker wanted to use the [[spigot mortar]] system. Instead of a barrel, there was a steel rod known as a "spigot" fixed to a baseplate, and the bomb itself had a propellant charge inside its tail. When the mortar was to be fired, the bomb was pushed down onto the spigot, which exploded the propellant charge and blew the bomb into the air.<ref name="Hogg42"/> By effectively putting the barrel on the inside of the weapon, the barrel diameter was no longer a limitation on the warhead size.<ref name="ODNB">{{Cite ODNB |last=Macrae|first=Stuart |url=http://www.oxforddnb.com/view/article/31907 |title=Blacker, (Latham Valentine) Stewart (1887–1964) |volume=1 |edition =revised |year=2004 |doi=10.1093/ref:odnb/31907 |access-date=27 April 2009}}</ref> Blacker eventually designed a lightweight mortar that he named the "Arbalest" and submitted it to the [[War Office]],{{sfn |Edgerton|2011 |p=261}} but it was turned down in favour of a Spanish design. Undeterred, however, Blacker continued with his experiments and decided to try to invent a hand-held anti-tank weapon based on the spigot design, but found that the spigot could not generate sufficient velocity needed to penetrate armour. But he did not abandon the design, and eventually came up with the [[Blacker Bombard]], a swivelling spigot-style system that could launch a {{convert |20|lb|kg|0|adj=on}} bomb approximately {{convert |100|yd|m|-1}}. Although the bombs it fired could not actually penetrate armour, they could still severely damage tanks, and in 1940 a large number of Blacker Bombards were issued to the [[Home Guard (United Kingdom)|Home Guard]] as anti-tank weapons.<ref>Hogg, pp. 42–43</ref>

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When Blacker became aware of the existence of shaped charge ammunition, he realized that it was exactly the kind of ammunition he was looking for to develop a hand-held anti-tank weapon, as it depended upon the energy contained within itself, and not the sheer velocity at which it was fired.<ref name="Hogg43">Hogg, p. 43</ref> Blacker then developed a shaped charge bomb with a propellant charge in its tail, which fitted into a shoulder-fired launcher that consisted of a metal casing containing a large spring and a spigot; the bomb was placed into a trough at the front of the casing, and when the trigger was pulled the spigot rammed into the tail of the bomb and fired it out of the casing and up to approximately {{convert |140|m|yd}} away. Blacker called the weapon the "Baby Bombard", and presented it to the War Office in 1941.<ref name="Hogg43"/> However, when the weapon was tested it proved to have a host of problems; a War Office report of June 1941 stated that the casing was flimsy and the spigot itself did not always fire when the trigger was pulled, and none of the bombs provided exploded upon contact with the target.<ref>Hogg, pp. 43–44</ref>

At the time that he developed the Baby Bombard and sent it off the War Office, Blacker was working for a government department known as [[MD1]], which was given the task of developing and delivering weapons for use by guerrilla and resistance groups in Occupied Europe.<ref name="Hogg44">Hogg, p. 44</ref> Shortly after the trial of the Baby Bombard, Blacker was posted to other duties, and left the anti-tank weapon in the hands of a colleague in the department, [[Major (United Kingdom)|Major]] [[Millis Jefferis]].<ref name="Hogg44"/>

Jefferis took the prototype Baby Bombard apart on the floor of his office in MD1 and rebuilt it, and then combined it with a shaped charge mortar bomb to create what he called the "Jefferis Shoulder Gun". Jefferis then had a small number of prototype armour-piercing [[high-explosive anti-tank]] (HEAT) rounds made, and took the weapon to be tested at the Small Arms School at [[Bisley, Surrey#Rifle range|Bisley]].<ref name=Khan23>Khan, pp. 2–3</ref> A [[warrant officer]] took the Shoulder Gun down to a firing range, aimed it at an armoured target, and pulled the trigger; the Shoulder Gun pierced a hole in the target, but  also wounded the warrant officer when a piece of metal from the exploding round flew back and hit him.<ref name=Khan23/> Jefferis himself then took the place of the warrant officer and fired off several more rounds, all of which pierced the armoured target but without wounding him. Impressed with the weapon, the Ordnance Board of the [[Small Arms School Corps|Small Arms School]] had the faults with the ammunition corrected, renamed the Shoulder Gun as the Projector, Infantry, Anti Tank, and ordered that it be issued to infantry units as a hand-held anti-tank weapon.<ref>Khan, p. 4</ref> Production of the PIAT began at the end of August 1942.<ref name="Hogg44"/>

[[File:PIAT Projectile CMHM Brantford.jpg|thumb|right|PIAT [[High-explosive anti-tank|HEAT]] projectile, Canadian Military Heritage Museum, Brantford, Ontario (2007)]]There was disagreement over the name to be given to the new weapon. A press report in 1944 gave credit for both the PIAT and the Blacker Bombard to Jefferis. Blacker took exception to this and suggested to Jefferis that they should divide any award equally after his expenses had been deducted.{{sfn |Edgerton|2011|p=160}} The Ministry of Supply had already paid Blacker £50,000 for his expenses in relation to the Bombard and PIAT.{{sfn |Edgerton|2011|p=161}} Churchill himself got involved in the argument; writing to the secretary of state for war in January 1943 he asked "Why should the name 'Jefferis shoulder gun' be changed to PIAT? Nobody objected to the Boys rifle, although that had a rather odd ring." {{sfn |Edgerton|2011|p=161}} Churchill supported Jefferis claims, but he did not get his way.{{sfn |Edgerton|2011|p=161}} For his part Blacker received £25,000 from the [[Royal Commission on Awards to Inventors]].<ref name="ODNB"/>{{efn|The 1957 report of the commission identified awards to Blacker as £7000 in addition to interim £25,000 "already awarded" for the Bombard, Hedgehog, Piat, and Petard projectiles, and the PIAT projector and Petard spigot mortar (used on the Churchill tank). {{sfn|Cohen Commission|1957 |p=46}}}}