It crossed silently on a chilly winter evening over the southern Oregon coast, descending slowly, its ballast spent. The Japanese bomb-laden paper balloon collapsed into the Gearhart Mountain forest near the line separating Lake and Klamath Counties in south-central Oregon. The undercarriage of the 70-foot balloon slammed into the earth, its impact muffled by several inches of snow, which prevented a 33-pound high-explosive antipersonnel bomb from exploding.

This was only one of an estimated 6,000 balloon bombs, codenamed Fugo, launched by the Japanese Army from the main island of Honshu between November 1944 and April 1945. Flowing along the jet stream, their cargo of incendiary and high-explosive bombs reached North America in less than a week.

Finding the Pacific Stream

The origin of the Japanese balloon bombs dated back to the occupation of Manchuria in the early 1930s. The Japanese hoped to harass the Soviets across the Amur River, the border between Japanese-occupied Manchuria and Soviet Siberia, by dropping propaganda leaflets from those balloons. Though the plan was never carried out, Japanese military scientists gained valuable information about the complexity of balloon flights over considerable distances. The idea of eventually using balloons to transport special troops or deliver bombs held promise for the Japanese military.

In 1940, the Japanese purchased daily weather maps from the United States Weather Bureau after discovering the existence of an air current moving west to east from Japan to the North American continent at a high altitude. Traveling at over 30,000 feet, it was possible for a balloon launched from Japan to cross the Pacific Ocean in an optimum timeframe of three days. It was not until late in the war, with the beginning of long-distance American bombing of the Japanese home islands, that the United States and its allies learned about the existence and importance of the jet stream.

During the summer of 1942, some consideration was given to a new use of the balloon project on the island of Guadalcanal. The Japanese proposed to attach grenades to long lengths of piano wire that were held aloft by balloons in hopes of snaring U.S. Marine fighter planes as they took off from captured airfields on the island.

How to Make a Fire Balloon?

As the fortunes of the Japanese forces on the island turned against them in September 1942, the idea was redirected into a plan for transcontinental balloon bombing. The Japanese saw two distinct possibilities for success. By attacking the richly forested areas of the U.S. Pacific Northwest with incendiary devices, they hoped to tie up military and civilian resources as well as cost the Allies millions of dollars in damage. Of even greater importance, the Japanese believed that the panic created would have a great psychological impact on the citizens of the West Coast.

By this stage of the war, the Imperial naval forces were stretched to their limits. The valuable submarines that were left could not be spared for Tanaka’s experiments. However, he was not dissuaded. By early 1944, he had developed a 29.5-foot balloon composed of rubbercovered silk panels. This fabric made the balloon durable, leak proof, and most importantly, flexible enough to withstand expansion and contraction due to changes in air pressure.

The Army’s balloon had been developed separately. It was made of more economical paper and was eventually chosen for the continuation of the project. Only 34 of Tanaka’s rubber balloons were approved for launch, none of which contained explosives. Tanaka’s balloons carried only radiosondes to collect data and sand for ballast.

The Army’s paper balloon was lighter and easier to launch, could carry a larger payload, was less expensive, and was slightly larger at 32.8 feet in diameter. This paper balloon was held together by komyyaku-nori, an adhesive gum made from the arum root. It was made waterproof through the use of a lacquer-like substance made from the fermented juice of green persimmons. This unlikely delivery system was chosen to carry the cargo of destruction to America.

In addition to the four small incendiary bombs, the Japanese included one 33-pound high-explosive antipersonnel bomb with an instantaneous fuse. This bomb was designed to spread shrapnel up to 300 feet away.

Transcontinental Balloon Bombing Begins

On November 3, 1944, the first of 6,000 bomb-laden balloons lifted from their moorings and headed toward North America. Though the weather at that time of year was not conducive to starting forest fires, the Japanese hoped that panic would be the measure of their success. Even as the first balloons lifted off, General Kusaba was experimenting with larger balloons for a planned summer offensive strike when the woods would be tinder dry. Though the estimates vary, records indicate that a minimum of 6,000 balloons were launched over the six-month period between November 1944 and April 1945.

The first balloon was discovered on November 3, 1944, off the coast of San Pedro, California, by a U.S. Navy patrol craft. It was one of Tanaka’s rubberized silk models carrying a radio transmitter. The first recorded bombing from a balloon occurred on December 6, 1944, outside Thermopolis, Wyoming. The Independent Record, a weekly newspaper at Thermopolis, reported the incident. It was believed that the bomb was dropped from a plane. Witnesses reported seeing a parachute land with flares. The local authorities abandoned their search for the parachute, believing it to have been only a landing flare.

Less than a week later, a balloon with an unexploded bomb was discovered outside Libby, Montana. This one was reported in the December 14, 1944, issue of the Western News, a weekly newspaper in Libby. The story was picked up by both Time and Newsweek magazines for their New Year’s Day editions. The writers for both magazines were as puzzled by the purpose of the balloon as the people of Libby. In a follow-up story two weeks later, Newsweek, citing government sources, concluded that the reported balloons had a limited range of 400 miles and were probably launched from submarines.

On the evening of January 2, 1945, Mrs. Evelyn Cyr arrived home and witnessed an explosion in a field next to her house on Peach Street in Medford, Oregon. An investigation by military personnel from nearby Camp White revealed that the explosion was caused by a small incendiary bomb. This was one of the first recorded instances of balloon bombings in Oregon, the state in which the most incidents were recorded. The rest of the balloon and its deadly payload were not recovered in the Medford area.

American Response

Authorities were quick to act. A news blackout was issued, requesting the press not to print any news about the balloon attacks. Cooperation among military and civilian authorities was total. The military and several federal agencies, including the FBI, U.S. Forestry authorities, and the Department of Agriculture moved to defend against this new form of attack by the Japanese. It was agreed that any balloons or other materials that were recovered would be sent to either Cal-Tech University in Pasadena, California, or the Naval Research Laboratory.

Of immediate FBI concern was the potential that the Japanese were using balloons for biological warfare. Though a valid concern, there are no known records of any Japanese personnel suggesting the use of the balloons in this fashion.

Several defensive strategies were discussed by civilian and military authorities. The Western Defense Command stationed additional planes for coastal defense and about 2,700 troops for fire fighting at critical points to protect against further balloon attacks. Further media attention was squelched to prevent heightened anxiety among the general population of the western United States and Canada.

In February 1945, the Japanese added stories of massive fires and loss of life from balloon attacks to their propaganda broadcasts. Their stories were, of course, false. The Japanese high command had received no reports regarding the results of their unmanned flights. The official silence concerning the attacks was so complete that the Japanese did not know that some balloons had, in fact, successfully made the journey across the South Pacific until the war was over.

The Mysterious End of Project Fugo

The balloon attacks continued into April 1945. By the end of that month the launches were terminated. Two possible reasons for ending the Fugo project exist. First, the Japanese high command may have thought that none of the balloons were reaching North America because of the lack of press coverage. Second, the intensive American air raids over Japan may have destroyed factories that supplied needed materials for the balloons, most notably hydrogen gas. Destruction of railroads could have made it virtually impossible to deliver the necessary supplies to launch sites.

The number of reported balloon incidents topped 300 by the time the war ended. Though most of them came down in the Pacific Northwest with 45 in Oregon, 28 in Washington, 57 in British Columbia, and 37 in Alaska, many others were driven greater distances by the jet stream. One balloon fell on a farm in Kansas, and two were discovered as far south and east Texas.

Originally Published October 27, 2018.

This article originally appeared on the Warfare History Network.

Image: Wikimedia