An arsonist can do tremendous damage with one lighted match, David Hambling explains (in Swarm Troopers), and incendiaries may be the weapon of choice where the payload is limited:
Even a small fire can quickly spread to engulf a building, a city block, or a forest. This was how the Japanese hoped to inflict serious damage with the Fu-Go balloon bombs mentioned in Chapter 1.
The military have preferred to use incendiaries on a gigantic scale. In WWII in Europe, massed Allied bombers would attack first with high explosives to break open buildings, followed by a wave of incendiaries to start fires. In Japan the buildings were less solid, and Boeing B-29 Superfortresses carried out pure incendiary raids on Tokyo and other cities. They dropped the M-69, a hexagonal steel pipe three inches across and twenty inches long filled with a newly-invented jellied gasoline mixed with phosphorus known as napalm. The pipe was heavy enough to break through roof tiles and penetrate into the rooms below; a few seconds after impact, the M-69 threw out flaming gobbets of napalm, which stuck to anything and burned whatever they touched.
[…]
Thirty-eight M-69s were bundled together in a “cluster bomb” that split apart midair and scattered its contents over a wide area. Each B-29 carried forty clusters, making over fifteen hundred M-69s per aircraft.
The plan was to start so many fires at the same time that it would be impossible to extinguish them. It worked exactly as intended.
[…]
“We scorched and boiled and baked to death more people in Tokyo on that night of March 9-10 than went up in vapor at Hiroshima and Nagasaki combined,” claimed General Curtis LeMay. Although not quite accurate (the atomic bombs killed over 130,000, the Tokyo firebombing about 100,000), it shows how the atomic bomb was merely an extension of existing bombing.
[…]
In the right place, even a tiny incendiary would be practically guaranteed to start a fire. One ounce of napalm could be more effective than a dozen M-69s scattered at random, just as one aimed bullet is more effective than a thousand sprayed aimlessly.
This led to one of the most bizarre plans of the war, which makes even the Fu-Go look ordinary. It all started when biologist Dr. Lytle Adams noted that the humble bat might be capable of carrying “a sufficient quantity of incendiary material to ignite a fire.”
Project X-Ray involved capturing thousands of bats and putting them into a state of hibernation by refrigeration, taking advantage of the bats’ natural tendency to sleep when the temperature drops. Each bat could then be fitted with a tiny bomb. The bats were packed into special trays which were in turn fitted into bomb casings, which would be dropped on Japanese cities. Released mid-air the bats would naturally seek refuge and roost in the eaves of houses – after which the incendiary bomb carried by each bat would burst into flames.
The researchers found that a half-ounce bat could carry a load weighing more than itself. A suitable incendiary device was devised, a celluloid capsule filled with napalm with an igniter the size of a match head. It worked in a similar fashion to the static line used by parachutists that automatically pulls the ripcord. In this case, as soon as the bat flew free from the bomb it pulled a pin, releasing a chemical that ate through a wire and triggered the napalm in fifteen minutes.
[…]
Disaster struck at Carlsbad Auxiliary Airfield in a test when the bats were not supposed to be released. The X-Ray team was filming the effects of the bat bomb indoors. Live bombs were attached to six hibernating bats. The cameramen were warned that it would only take the bats a few minutes to warm up and become active again. Unfortunately the cameramen did not realize just how active bats can be. Frantic efforts failed to net any of the six armed bats and they flew off, seeking places to roost.
At least one of the six headed for a new control tower, another for a newly-built and unoccupied barracks building. Exactly fifteen minutes after the bombs were armed, both structures burst into flames. The fire rapidly spread in the dry desert conditions, consuming hangars and offices. It was too late to save the airfield buildings, but not too late to maintain security. Baffled firefighters who arrived to tackle the blaze were turned back from the gates while the buildings continued to burn. A few days later the burned remains were bulldozed to hide the evidence.
