After the Korean War, a safer but equally effective napalm formulation was developed, which used a combination of polystyrene (46%) and benzene (21%) added to gasoline (33%). The newer formulation was known as Napalm-B, Super Napalm, or NP2, despite containing neither naphthalene nor palmitic acids. Therefore, the United States Army technically speaking did not use napalm during the Vietnam War, rather the newer formulation Napalm-B. In 1965, the Dow Chemical Company began manufacturing Napalm-B for the United States military which ultimately led to a nationwide campaign of protests against the company. Despite the protests, Dow Chemical continued to manufacture Napalm-B for the U.S. military until its contract expired in 1969.
Napalm-B had one major advantage over its predecessor, its ignition could be readily controlled. It was more difficult to ignite due to the inclusion of polystyrene in the compound. Napalm-B was typically combined with thermite, sodium, magnesium and phosphorous and could produce temperatures ranging from 1500-2000 degrees Celsius (2732-3632 degrees Fahrenheit). It was relatively easy to manufacture and could be used in grenades, aerial bombs, flamethrowers, artillery shells, missiles and tank canons.
Napalm-B was first used by American and South Vietnamese Army soldiers to clear out bunkers, foxholes, and trenches. Napalm fires rapidly deoxygenate the air around them and increase the amount of carbon monoxide and carbon dioxide in the air, so even if its flames were unable to penetrate deeply enough into an enemy bunker, trench or foxhole, it would suffocate those inside.
One of the principal uses of Napalm-B in the Vietnam War was to destroy forest cover and food supplies. It was also used for close air support during search-and-destroy operations and against North Vietnamese troops and material marshaling areas. American bombers dropped Napalm-B bombs in large canisters which exploded on impact, engulfing the surrounding area in flames.
Napalm bombs were preferred to conventional high explosive bombs where careful targeting was required, as they could be dropped from a much lower altitude. One drawback of dropping Napalm-B from high-speed jet aircraft was that it wasn’t a very accurate way of targeting enemy positions and occasionally resulted in cases of “friendly fire” where Allied forces would inadvertently become its victims. North Vietnamese forces quickly learned that the best tactic to deploy was to stay close to Allied targets in combat, to avoid being bombed.
Napalm-B was also used by Vietnamese fighter escort aircraft to clear landing zones for helicopters, often just a short time before the helicopter arrived, making landing hazardous. Napalm-B was also used in a defensive capacity during the Vietnam War by Allied forces, in base camp and fire base perimeter defense. Barrels containing napalm would be buried under concertina wire (coils of barbed wire approximately two to three feet high) around the perimeter of the defensive position. These barrels would be detonated when under attack, incinerating the enemy.
Between 1963-1973, the U.S. dropped 388,000 tons of napalm on North Vietnamese targets. The prevalence of napalm as a weapon during the Vietnam War can be seen when compared with figures in previous wars which saw American involvement, 32,357 tons were dropped during the Korean War, and 16,500 tons in the Pacific.