Lauded as a success story following its use in the Korean War and the latter stages of World War II, napalm’s reputation as a weapon changed dramatically from its early years of acclaim to one of notoriety, most notably during the Vietnam War. Jungles engulfed in flames became iconic images of the conflict, but it was the images of napalm’s civilian casualties which led to a national campaign calling for a ban on its use and a boycott of its manufacturer, the Dow Chemical company.
During the early months of World War II, the U.S. Chemical Warfare Service used latex from the Para rubber tree to thicken gasoline for incendiaries. By the time the U.S. entered the war in the Pacific, natural rubber was in short supply due to the capture of rubber plantations in Malaya, Indonesia, Vietnam, and Thailand by the Japanese Army. Research teams at Harvard University, Du Pont, and Standard oil competed to develop a replacement for natural rubber for the United States government.
Napalm was first developed by a team of chemists led by Louis F. Fieser in 1942 at Harvard University in a top-secret war research collaboration with the United States government. Napalm in its original composition was formed by mixing a powdered aluminum soap of naphthalene with palmitate, from which napalm gets its name. Naphthalene, also known as naphthenic acids is a corrosive found in crude oil while palmitate, or palmitic acid, is a fatty acid which occurs naturally in coconut oil.
When added to gasoline it acted as a gelling agent which allowed for more effective propulsion from incendiary weapons. Napalm tripled the range of flamethrowers and increased the amount of burning material delivered to a target almost tenfold. However, the devastating effects of napalm as a weapon were fully realized when it was used as an incendiary bomb.
Napalm became a very popular choice of weapon with the military due to its many advantages. Napalm burns for longer and at a higher temperature than gasoline. It was relatively cheap to manufacture, and its naturally adhesive properties made it a more effective weapon, as it stuck to its target. A napalm bomb was also capable of destroying a 2500 square yard area. Napalm was lauded as much for its psychological effects of instilling terror in the enemy as for its effectiveness at breaching fortifications or destroying targets.
The U.S. Army Air Force first used a napalm bomb in an attack on Berlin on March 6, 1944 during World War 11. American bombers went on to use napalm against Japanese fortifications, such as bunkers, pillboxes, and tunnels, in Saipan, Iwo Jima, the Philippines and Okinawa between 1944-45. But it was on the night of March 9-10, 1945, in one of the most destructive bombing raids in human history, where napalm realised its true devastating potential. 279 American B-29 bombers dropped 690,000 pounds of napalm on Tokyo, engulfing the city’s wooden buildings in an inferno which destroyed 15.8 square miles of the city and killed approximately 100,000 people while leaving over one million people homeless. For the next eight days, U.S. bombers targeted every major Japanese city (with exception of Kyoto) until stocks of napalm ran out.
Napalm was seen as a vital strategic weapon in the Korean War where it was used to support Allied ground forces locally outnumbered by North Korean and Chinese forces. American bombers dropped approximately 250,000 pounds of napalm per day during the Korean War.