During World War II the United States military wanted a more efficient fuel than liquid gasoline for its flame throwers. In 1942 a team of chemical researchers at Harvard University led by Louis F. Fieser developed an inexpensive and readily available gelling agent from naphthenic acid, a petroleum distillate, and palmitic acid, hydrolyzed from palm oil. The new compound, called napalm, was mixed with gasoline to make a thicker, slower-burning fuel that could be projected farther and more accurately. This is napalm. It is a deadly chemical, clinging to whatever it touches and burning with a ferocious tenacity.

Napalm was soon adapted for other military purposes, particularly as incendiary filler for fire bombs. The Allied air forces first used it against Japanese industrial targets and at Guadalcanal. During the Korean War, napalm land mines were used. Its use continued in Vietnam, where it proved especially effective as a defoliant. Dropped from an airplane, napalm ignited large areas. The use of napalm against civilians in Vietnam contributed greatly to the unpopularity of that war, and a widely published photograph of a naked child escaping from her burning village was one of the most sinister images of the time.

Vietnam-era napalm has since been replaced by napalm-B, which consists of a polystyrene thickener, benzene, and gasoline. Napalm-B is even more lethal than its predecessor, burning hotter and longer. The United States dropped 15,000-lb (6,804 kg) bombs of "jellied slurry," a napalm-like substance during the Persian Gulf War to clear areas on the ground for its helicopters. In 1998, the United States Navy was faced with the task of disposing of thousands of gallons of napalm that it had kept in storage for almost thirty years. The dangerous chemical is difficult to recycle or destroy harmlessly.