White phosphorus (weapon)
From Wikipedia, the free encyclopedia
- This article is about the military applications of white phosphorus. For more general information, see Phosphorus.
White phosphorus is a common allotrope of the chemical element phosphorus which has found extensive military application as an incendiary agent,[1] smoke-screening agent, and as an antipersonnel flame compound capable of causing serious burns.[2] White Phosphorus (WP) bombs and shells are essentially incendiary devices, and can be used in an offensive anti-personnel role against enemy troop concentrations. It is used in bombs, artillery shells, and mortar shells which burst into burning flakes of phosphorus upon impact. White phosphorus has been described as a chemical weapon, but because it can be used as a multi-purpose device to mark targets, provide a smoke screen, or signal to friendly troops, it is not covered by UN protocols on incendiary weapons. It is commonly referred to in military jargon as "WP". The Viet Nam-era slang "Willy(ie) Pete" or "Willy(ie) Peter" is still occasionally heard. In recent years, employment of WP weapons has declined with the increased effectiveness of modern proximity-fused anti-personnel and anti-armor fragmentation shells, bomblets, and missiles.
Contents |
[edit] History
WP is believed to have been first used by Fenian arsonists in the 19th century in the form of a solution of WP in carbon disulfide. When the carbon disulfide evaporated, the WP would burst into flames, and probably also ignite the highly flammable carbon disulfide fumes. This mixture was known as "Fenian fire" and allegedly was also used by I.W.W. activists in the early 20th century.
[edit] World War I and II
Britain's army introduced its first factory-built WP grenades in late 1916. In World War II, white phosphorus mortar bombs, shells, rockets and grenades were used extensively by American, Commonwealth, and to a lesser extent Japanese forces, in both smoke-generating and antipersonnel roles. In 1940, when the invasion of Britain seemed imminent, the phosphorus firm of Albright and Wilson suggested that the British government use a material similar to Fenian fire in several expedient incendiary weapons. The only one fielded was the Grenade, No. 76 or Special Incendiary Phosphorus grenade, which consisted of a glass bottle filled with a mixture similar to Fenian fire, plus some latex (c.f. Molotov cocktail, Greek fire). It came in two versions, one with a red cap intended to be thrown by hand, and a slightly stronger bottle with a green cap, intended to be launched from the Northover projector (a crude 2.5 inch blackpowder grenade launcher). Instructions on each crate of SIP grenades included the observations, inter alia:
- Store bombs (preferably in cases) in cool places, under water if possible.
- Stringent precautions must be taken to avoid cracking bombs during handling.
It was generally regarded as overly dangerous to its own operators.
At the start of the Normandy campaign, 20% of American 81 mm mortar rounds were WP. At least five American Medal of Honor citations mention their recipients using white phosphorus grenades to clear enemy positions. In the 1944 liberation of Cherbourg alone, a single U.S. mortar battalion, the 87th, fired 11,899 white phosphorus rounds into the city.
The U.S. Army and Marines used WP shells in large 4.2-inch chemical mortars. WP was widely credited by Allied soldiers for breaking up German infantry attacks and creating havoc among enemy troop concentrations during the latter part of the war. The psychological impact of WP on the enemy was noted by many troop commanders in WWII, and captured 4.2-inch mortar crews were sometimes summarily executed by German forces in reprisal.
Incendiary bombs were used extensively by the German, British and US air forces against civilian populations and targets of military significance in civilian areas (Hamburg, Dresden, Area bombing etc). Late in the war, some of these bombs used white phosphorus (about 1-200 grams) in place of magnesium as the igniter for their flammable mixtures. The use of incendiary weapons against civilians was eventually banned (by signatory countries) in the 1980 United Nations Convention on Certain Conventional Weapons Protocol III. The USA has signed Articles I and II, but was not a signatory to Protocols III, IV, and V.
[edit] Others
WP munitions were used extensively in Korea, Vietnam and later by Russian forces in Chechnya. According to GlobalSecurity.org, "In the December 1994 battle for Grozny in Chechnya, every fourth or fifth Russian artillery or mortar round fired was a smoke or white phosphorus round."
WP was used by the Argentine Army during the 1989 attack on La Tablada Regiment, in a violation of the Geneva Convention (according to a document presented by the human rights commission of the United Nations on January 12, 2001) [3].
[edit] Iraq War
- Main article: White phosphorus use in Iraq
The United States Army has acknowledged using these bombs in the Iraq War in areas such as Fallujah.[4] After the diffusion on November 8, 2005 of Fallujah, The Hidden Massacre, a documentary film by Sigfrido Ranucci on Italy's RaiNews24, which accused the US Army of having use in an offensive manner white phosphorus, as a chemical weapon, Dept. of Defense spokesman Lieutenant-Colonel Barry Venable confirmed to the BBC on November 15 that WP had been used as an antipersonnel weapon in Fallujah:[5] Venable pointed out that WP was effective against enemy forces in covered positions that were protected from high explosives. "One technique is to fire a white phosphorus round into the position because the combined effects of the fire and smoke - and in some case the terror brought about by the explosion on the ground - will drive them out of the holes so that you can kill them with high explosives."
On November 30, 2005, General Peter Pace defended use of WP, declaring that WP munitions were a "legitimate tool of the military", used to illuminate targets and create smokescreens, adding: "It is not a chemical weapon. It is an incendiary. And it is well within the law of war to use those weapons as they're being used, for marking and for screening". Peter Pace argued that conventional weapons can be more dangerous than non-conventional weapons: "A bullet goes through skin even faster than white phosphorus does".[6]
[edit] 2006 Israel-Lebanon conflict
During the 2006 Israel-Lebanon conflict, Israel used phosphorus shells "against military targets in open ground" in south Lebanon. Israel stated that its use of the White Phosphorous bombs was permitted under international conventions.[7] President of Lebanon Émile Lahoud claimed that phosphorus shells were used against civilians in Lebanon. Several media sources had reported they had seen Lebanese civilians with injuries characteristic of phosphorus.[8]
[edit] Smoke-screening properties
Weight-for-weight, phosphorus is the most effective smoke-screening agent known, for two reasons: first, it absorbs most of the screening mass from the surrounding atmosphere and secondly, the smoke particles are actually an aerosol, a mist of liquid droplets which are close to the ideal range of sizes for Mie scattering of visible light. This effect has been likened to three dimensional textured privacy glass—the smoke cloud does not obstruct an image, but thoroughly scrambles it. It also absorbs infrared radiation.
When phosphorus burns in air, it first forms phosphorus pentoxide (which exists as tetraphosphorus decoxide except at very high temperatures):
- P4 + 5 O2 → P4O10
However phosphorus pentoxide is extremely hygroscopic and quickly absorbs even minute traces of moisture to form liquid droplets of phosphoric acid:
- P4O10 + 6 H2O → 4 H3PO4 (also forms polyphosphoric acids such as pyrophosphoric acid, H4P2O7)
Since an atom of phosphorus has an atomic mass of 31 but a molecule of phosphoric acid has a molecular mass of 98, the cloud is already 68% by mass derived from the atmosphere (i.e. you have 3.2 kilograms of smoke for every kilogram of WP you started with); however, it may absorb more because phosphoric acid and its variants are hygroscopic. Given time, the droplets will continue to absorb more water, growing larger and more dilute until they reach equilibrium with the local water vapour pressure. In practice, the droplets quickly reach a range of sizes suitable for scattering visible light and then start to dissipate from wind or convection.
Because of the great weight efficiency of WP smoke, it is particularly suited for applications where weight is highly restricted, such as hand grenades and mortar bombs. An additional advantage for hand smoke grenades—which are more likely to be used in an emergency—is that the WP smoke clouds form in a fraction of a second. Because WP is also pyrophoric, most munitions of this type have a simple burster charge to split open the casing and spray fragments of WP through the air, where they ignite spontaneously and leave a trail of rapidly thickening smoke behind each particle. The appearance of this cloud forming is easily recognised; one sees a shower of burning particles spraying outward, followed closely by distinctive streamers of white smoke, which rapidly coalesce into a fluffy, very pure white cloud (unless illuminated by a coloured light source).
Various disadvantages of WP are discussed below, but one which is particular to smoke-screening is "pillaring". Because the WP smoke is formed from fairly hot combustion, the gasses in the cloud are hot, and tend to rise. Consequently the smoke screen tends to rise off the ground relatively quickly and form aerial "pillars" of smoke which are of little use for screening. Tactically this may be counteracted by using WP to get a screen quickly, but then following up with emission type screening agents for a more persistent screen. Some countries have begun using red phosphorus instead. Red phosphorus ("RP") burns cooler than WP and eliminates a few other disadvantages as well, but offers exactly the same weight efficiency. Other approaches include WP soaked felt pads (which also burn more slowly, and pose a reduced risk of incendiarism) and PWP, or plasticised white phosphorus.
[edit] Effects on humans
White phosphorus can cause injuries and death in three ways: by burning deep into soft tissue, by being inhaled as a smoke and by being ingested. Extensive exposure in any way can be fatal.
[edit] Effects of exposure to WP weapons
Incandescent particles of WP cast off by a WP weapon's initial explosion can produce extensive, deep (second and thirdcompletely WP particles do not burn (WP) (Global Security.org) | url=http://www.globalsecurity.www. particularly dangerous to exposed people because white phosphorus continueatsdr.cdc.gov/tcom toxicity profiles (pdf)]</ref> These weapons ares to burn bone. In some he body through the burned area, resulting oxygen or until it is completely consumed, in some cmunitions/wp.htm | accessmonthday=December 4 | ac472">{{due to the absorption of phosphorus into tchemical burnpersonal clothing before being consumed. According to [[GlobalSecuunless has been add deleted on and on.-->. name="www.globalsecurity.org.Phosphocite web | title=White cessyear=2005 }}</ref>
