Napalm is an incendiary weapon made by thickening gasoline into a sticky gel that burns at extremely high temperatures and clings to surfaces, including skin. First created in 1942 at a secret Harvard University laboratory by chemist Louis Fieser and his team, it was designed specifically to start large, persistent fires that are nearly impossible to extinguish. The name itself comes from two of the original gelling agents: naphthenate and palmitate.
How Napalm Works
Ordinary gasoline burns fast and spreads thin. Napalm solves that problem (from a military standpoint) by turning gasoline into a thick, jelly-like substance that sticks where it lands and burns far longer. The original formula used a powder made from aluminum soaps of coconut acids to thicken the fuel. When ignited, the gel burns intensely while adhering to structures, vegetation, and people.
The later version, known as Napalm-B, replaced the original gelling approach with a different chemistry: 50% polystyrene (a common plastic), 25% benzene, and 25% gasoline. This reformulation made the weapon even more effective. The polystyrene acts as both a thickener and a fuel source, creating a substance that burns hotter and longer than the original. Napalm-B also sticks more aggressively to surfaces, making it harder to remove or extinguish with water.
What Napalm Does Beyond the Fire
The burning gel itself is only part of what makes napalm so destructive. When it ignites, it rapidly consumes oxygen from the surrounding air, which can cause suffocation even for people not directly hit by the flames. In enclosed or semi-enclosed spaces, this oxygen depletion can cause loss of consciousness and death within minutes.
The combustion also produces dangerously high levels of carbon monoxide and carbon dioxide. Normal air contains a trace amount of carbon dioxide, and concentrations around 4% can be fatal within roughly an hour. Burning napalm generates carbon dioxide concentrations near 20%, five times the lethal threshold. Combined with the oxygen depletion and carbon monoxide poisoning, napalm creates a toxic environment that extends well beyond the visible fire zone.
Effects on the Human Body
Napalm was, as Harvard University Press described it, “explicitly designed to destroy civilian targets.” Its effects on the human body are severe. Because the gel adheres to skin, victims cannot simply brush it off or smother the flames. It burns deep into tissue, capable of reaching bone. The resulting injuries are a combination of extreme thermal burns, chemical damage from the petroleum compounds, and systemic poisoning from inhaling combustion byproducts.
Survivors of napalm burns face extensive scarring and tissue damage. The burns typically penetrate far deeper than those from ordinary fires because the fuel stays in contact with the body rather than falling away. Treatment follows the same general principles as other severe burns: removing the person from the exposure, stripping away clothing and contaminated material, and irrigating wounds with large amounts of water as quickly as possible. Starting water irrigation immediately, before reaching a hospital, reduces burn severity and shortens recovery time. But the reality is that serious napalm injuries often overwhelm standard burn care.
Where and When It Has Been Used
Napalm entered combat during World War II, where Allied forces used it extensively in both the European and Pacific theaters. Incendiary bombing raids on Japanese cities in 1945, particularly the firebombing of Tokyo in March of that year, killed tens of thousands of civilians and leveled vast urban areas. The weapon’s ability to start uncontrollable fires across wide areas made it devastatingly effective against the wooden construction common in Japanese cities.
Its most well-known use came during the Vietnam War, where American forces dropped massive quantities of Napalm-B on both military positions and jungle terrain. The goal was twofold: to destroy enemy cover and to deny guerrilla fighters the dense vegetation they used for concealment. Images from Vietnam, particularly the 1972 photograph of nine-year-old Phan Thi Kim Phúc running from a napalm strike, became some of the most powerful anti-war symbols of the 20th century. The Korean War also saw extensive napalm use against both military and civilian targets.
Legal Status
The United Nations Convention on Certain Conventional Weapons, adopted in 1980, includes Protocol III, which restricts the use of incendiary weapons against civilians and against military targets located within concentrations of civilians. The protocol does not ban napalm outright but prohibits using air-delivered incendiary weapons against military objectives located in civilian areas. Ground-delivered incendiary weapons face fewer restrictions under the same protocol.
The United States signed the convention but has not ratified Protocol III, meaning it is not legally bound by its specific restrictions on incendiary weapons. Several other major military powers have similarly declined to ratify this particular protocol, leaving the legal framework around napalm and similar weapons incomplete by international standards.