Napalm was used in flamethrowers and firebombs by the U.S. and Allied forces. Napalm is made to burn at a specific rate and stick to materials. This is done by mixing different amounts of napalm and other materials. Another useful (and dangerous) effect, primarily involving its use in bombs, was that napalm "rapidly deoxygenates the available air." It also creates large amounts of carbon monoxide causing suffocation. Napalm bombs were also used in the Vietnam War to clear landing zones for helicopters.
Though napalm was a 20th-century invention, it is part of a long history of incendiary devices in warfare. However, historically, it was primarily liquids that were used (see Greek fire). An infantry-based flammable liquid fuel weapon, the flamethrower, was introduced in World War I by the Germans, variations of which were soon developed by other sides in the conflict.
On July 17, 1944, napalm incendiary bombs were dropped for the first time by American P-38 pilots on a fuel depot at Coutances, near St. Lô, France. Napalm bombs were first used in the Pacific Theatre during the Battle of Tinian by Marine aviators. Its use was complicated by problems with mixing, fusing and the release mechanisms. In World War II, Allied forces bombed cities in Japan with napalm, and used it in bombs and flamethrowers in Germany and the Japanese-held islands. It was used by the Greek army against communist guerrilla fighters during the Greek Civil War, by United Nations forces in Korea, by Mexico in the late 1960s against guerrilla fighters in Guerrero and by the United States during the Vietnam War.
The most well-known method of delivering napalm is from air-dropped incendiary bombs. A lesser-known method is the flame throwers used by combat infantry. Flamethrowers use a thinner version of the same fuel to destroy gun emplacements, bunkers and cave hideouts. U.S. Marines fighting on Guadalcanal found them very effective against Japanese positions. The Marines used fire as both a casualty weapon as well as a psychological weapon. Men have a natural fear of fire. They found that Japanese soldiers would abandon positions in which they fought to the death against other weapons. Prisoners of war confirmed that they feared napalm more than any other weapon thrown at them.
Napalm became one of the preferred weapons of the Korean War. Pilots returning from the war zone often remarked they would rather have a couple of gasoline tanks full of napalm to drop than any other weapon, bombs, rockets or guns. The U.S. Air Force and Navy used napalm with great effect against all manner of targets to include troops, tanks, buildings and even rail road tunnels. The demoralizing effect napalm had on the enemy became apparent when scores of North Korean troops began to surrender to aircraft flying overhead. Pilots noted they saw surviving enemy troops waving white flags on subsequent passes after dropping napalm. The pilots radioed to ground troops and the North Koreans were captured.
Napalm has been used recently in wartime by or against: Iran (1980–88), Israel (1967, 1982), Nigeria (1969), Brazil (1972), Egypt (1973), Cyprus (1964, 1974), Argentina (1982), Iraq (1980–88, 1991, 20th March 2003 – 15th December 2011), Serbia (1994), Turkey (1963, 1974, 1997), Angola, United States.
In some cases, napalm disables and kills its victims very quickly. Those who do survive suffer up to 5th degree burns. These damage parts of the skin which do not have pain receptors. However, victims who suffer 2nd degree burns from splashed napalm will be in significant amounts of pain.
Philip Jones Griffiths describes its use in Vietnam:
Phuc had third-degree burns to half her body and was not expected to live. But thanks to assistance from South Vietnamese photographer Nick Ut, and after surviving a 14-month hospital stay and 17 operations, she became an outspoken peace activist.
International law does not prohibit the use of napalm or other incendiaries against military targets, but use against civilian populations was banned by the United Nations' inhumane weapons convention (often referred to as the CCW) in 1981. Protocol III of the CCW restricts the use of incendiary weapons (not only napalm), but a number of states have not acceded to all of the protocols of the CCW. According to the Stockholm International Peace Research Institute (SIPRI), states are considered a party to the convention, which entered into force as international law in December 1983, if they ratify at least two of the five protocols. The United States, for example, is a party to the CCW but did not sign Protocol III.
Reports by the "Sydney Morning Herald" suggested that "napalm" has been used in the Iraq War by US forces. The U.S. Department of Defense denied this. In August 2003, the San Diego Union Tribune said that U.S. Marine pilots and their commanders confirmed the use of Mark 77 firebombs on Iraqi Republican Guards during the start of combat. Official denials of the use of 'napalm' were, however, disingenuous, as the Mk 77 bomb that is currently in service at this time, the Mk 77 Mod 5, does not use actual napalm (e.g. napalm-B). The last U.S. bomb to use actual napalm was the Mark 77 Mod 4, the last of which were destroyed in March 2001. The substance used now is a different incendiary mixture. It is sufficiently analogous in its effects that it is still a controversial incendiary, and can still be referred to colloquially as 'napalm.'
"We napalmed both those (bridge) approaches," said Col. Randolph Alles in a recent interview. "Unfortunately, there were people there because you could see them in the (cockpit) video." (...) "They were Iraqi soldiers there. It's no great way to die," he added. (...) The generals love napalm. ... It has a big psychological effect." - "San Diego Union-Tribune, August 2003"
These bombs did not actually have napalm in them. The napalm-B (super napalm) used in Vietnam was gasoline based. The Mk-77 firebombs used in the Gulf were kerosene based. It is, however, a napalm-like liquid in its effect.
Recipes how to make napalm-like substances can be found on the Internet. Very often, the recipes say that they will make a thick substance using gasoline, with soap or polystyrene as a thickening agent. However, inexperienced people following these instructions often handle the substance improperly and cause accidents. In addition, making incendiary devices is illegal in many countries.
Napalm is usually a mixture of gasoline with suitable thickening agents. The earliest thickeners were soaps, aluminum, and magnesium palmitates and stearates. Depending on how much thickener is added, the resulting viscosity may range between syrupy liquid and thick rubbery gel. The content of long hydrocarbon chains makes the material highly hydrophobic (resistant to wetting with water), making it more difficult to extinguish. Thickened fuel also rebounds better from surfaces, making it more useful for operations in urban terrain.
There are two types of napalm: oil-based with aluminium soap thickener, and oil-based with polymeric thickener ("napalm-B").
The United States military uses three kinds of thickeners: M1, M2, and M4.
A later variant, napalm-B, also called "super napalm", is a mixture of low-octane gasoline with benzene and polystyrene. It was used in the Vietnam War. Unlike conventional napalm, which burns for only 15–30 seconds, napalm B burns for up to 10 minutes with fewer fireballs. It also sticks better to surfaces, and offers improved destruction effects. It is not as easy to ignite. This reduces the number of accidents caused by soldiers smoking. When it burns, it develops a characteristic smell.
Starting in the early 1990s, various websites including The Anarchist Cookbook advertised recipes for homemade napalm. These recipes were predominantly equal parts gasoline and styrofoam. This mixture closely resembles that of napalm-B, but lacks a percentage of benzene.