Incendiary Device - Development and Use in World War II

Development and Use in World War II

Incendiary bombs were used extensively in World War II as an effective bombing weapon, often in a conjunction with high-explosive bombs. Many different configurations of incendiary bombs and a wide range of filling materials such as isobutyl methacrylate (IM) polymer, Napalm and similar jellied-petroleum formulae were used, many of them developed by the US Chemical Warfare Service. Different methods of delivery, e.g. small bombs, bomblet clusters and large bombs, were tested and implemented. For example, a large bomb casing was filled with small sticks of incendiary (bomblets); the casing was designed to open at altitude, scattering the bomblets in order to cover a wide area. An explosive charge would then ignite the incendiary material, often starting a raging fire. The fire would burn at extreme temperatures that could destroy most buildings made of wood or other combustible materials (buildings constructed of stone tend to resist incendiary destruction unless they are first blown open by high explosives).

Originally, incendiaries were developed in order to destroy the many small, decentralized war industries located (often intentionally) throughout vast tracts of city land in an effort to escape destruction by conventionally-aimed high-explosive bombs. Nevertheless, the civilian destruction caused by such weapons quickly earned them a reputation as terror weapons (e.g., German Terrorflieger) with the targeted populations, and many shot-down aircrews were summarily executed by angry civilians upon capture. The Nazi regime began the campaign of incendiary bombings with the bombing of targets in London in 1940–41, and an extensive reprisal was exacted by the Allies in the strategic bombing campaign that lead to the annihilation of most major German cities. In the Pacific War, during the last seven months of strategic bombing by B-29 Superfortresses in the airwar against Japan, a change to firebombing tactics resulted in some 500,000 Japanese deaths and 5 million more made homeless. Sixty-seven of Japan's largest cities lost significant area to incendiary attacks. The most deadly single bombing raid in all history was Operation Meetinghouse, an incendiary attack that killed some 100,000 Tokyo residents in one night.

The 4 lb (1.8 kg) incendiary bomb was the standard light incendiary bomb used by Bomber Command in very large numbers, declining slightly in 1944 to 35.8 million bombs produced (the decline being due to more bombs arriving from the USA). It was the weapon of choice for the British dehousing plan. The bomb consisted of a magnesium body with a cast iron/steel nose, and it was filled with thermite incendiary pellets and was capable of burning for up to ten minutes, the magnesium body adding to the incendiary effect. There was also a high explosive version and delayed high explosive versions (2–4 minutes) which were specifically designed to kill rescuers. Other tactics consisted of using explosive bombs in the attack to fill the streets with craters and rubble, hindering rescue services. Towards the end of World War Two, the British introduced a much improved 30 lb (14 kg) incendiary bomb, whose fall was retarded by a small parachute and on impact sent out an extremely hot flame for 15 ft (4.6 m); it burned for approximately two minutes. Articles in late 1944 claimed that the flame was so hot it could crumble a brick wall. And for propaganda purposes the RAF dubbed the new incendiary bomb the Superflamer. Very little else is known about this new incendiary bomb that came into operational service late in the war in the European theater.

Many incendiary weapons developed and deployed during World War II were in the form of bombs and shells whose main incendiary component is white phosphorus (WP), and can be used in an offensive anti-personnel role against enemy troop concentrations, but WP is also used for signaling, smokescreens, and target-marking purposes. The U.S. Army and Marines used WP extensively in WWII and Korea for all three purposes, frequently using WP shells in large 4.2-inch chemical mortars. WP was widely credited by many Allied soldiers for breaking up numerous German infantry attacks and creating havoc among enemy troop concentrations during the latter part of WWII. The psychological impact of WP on the enemy was noted by many troop commanders in WWII, and captured 4.2-inch mortar men were sometimes summarily executed by German forces in reprisal. In both WWII and Korea, WP was found particularly useful in overcoming enemy human wave attacks.