page_title: White phosphorus munitions
section_title: World War I, the inter-war period and World War II
hierarchical_section_title: White phosphorus munitions / World War I, the inter-war period and World War II
caption_attribution_description: English: A white phosphorus bomb explodes on a mast top, while the ship in use as a target in Chesapeake Bay, 23 September 1921. An Army Martin twin-engine bomber is flying overhead. U.S. Naval History and Heritage Command Photograph.
context_page_description: White phosphorus munitions are weapons which use one of the common allotropes of the chemical element phosphorus. White phosphorus is used in smoke, illumination and incendiary munitions, and is commonly the burning element of tracer ammunition. Other common names include WP and the slang term "Willie Pete" or "Willie Peter" derived from William Peter, the World War II phonetic alphabet for "WP", which is still sometimes used in military jargon. White phosphorus is pyrophoric, burns fiercely, and can ignite cloth, fuel, ammunition, and other combustibles.
  In addition to its offensive capabilities, white phosphorus is a highly efficient smoke-producing agent, reacting with air to produce an immediate blanket of phosphorus pentoxide vapor. As a result, smoke-producing white phosphorus munitions are very common, particularly as smoke grenades for infantry, loaded in defensive grenade launchers on tanks and other armoured vehicles, and as part of the ammunition allotment for artillery or mortars. These create smoke screens to mask friendly forces' movement, position, infrared signatures, or shooting positions.
context_section_description: The British Army introduced the first factory-built WP grenades in late 1916. During World War I, 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. The British military also used white phosphorus bombs against Kurdish villagers and Al-Habbaniyah in Al-Anbar province during the Great Iraqi Revolution of 1920.
  In the interwar years, the US Army trained using white phosphorus, by artillery shell and air bombardment.
  In 1940, when the invasion of the British home islands 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. 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 launcher using black powder as a propellant). These were improvised anti-tank weapons, hastily fielded in 1940 when the British were awaiting a German invasion after losing the bulk of their modern armaments in the Dunkirk evacuation.
  At the start of the Normandy campaign, 20% of American 81 mm mortar ammunition consisted of M57 point-detonating bursting smoke rounds using WP filler. At least five American Medal of Honor citations mention their recipients using M15 white phosphorus hand grenades to clear enemy positions, and in the 1944 liberation of Cherbourg alone, a single US mortar battalion, the 87th, fired 11,899 white phosphorus rounds into the city. The US Army and Marines used M2 and M328 WP shells in 107mm (4.2 inch) mortars. White phosphorus was widely used by Allied soldiers for breaking up German attacks and creating havoc among enemy troop concentrations during the latter part of the war.  
  US Sherman tanks carried the M64, a 75mm white phosphorus round intended for screening and artillery spotting, but tank crews found it useful against German tanks such as the Panther that their APC ammunition could not penetrate at long range. Smoke from rounds fired directly at German tanks would be used to blind them, allowing the Shermans to close to a range where their armour-piercing rounds were effective. In addition, due to the turret ventilation systems sucking in fumes, German crews would sometimes be forced to abandon their vehicle: this proved particularly effective against inexperienced crews who, on seeing smoke inside the turret, would assume their tank had caught fire. Smoke was also used for "silhouetting" enemy vehicles, with rounds dropped behind them to produce a better contrast for gunnery.
caption: Air burst of a white phosphorus bomb over the USS Alabama (BB-8) during a test exercise conducted by General Billy Mitchell, September 1921
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