Seattle, Washington · November 3, 1944

On this date in 1944 Japan began an explosive balloon cam­paign against the U.S. and Canada. Over the next five months the Special Bal­loon Regi­ment of the Japa­nese Army launched about 9,300 hydro­gen-filled rubberized-silk or paper “fire bal­loons” (fūsen bakudan, lit. “balloon bomb”), or Fu-Go’s as they were known in Japan, from the esst­ern shore of Honshū Island. Made mostly by school girls and carried by the high-alti­tude jet stream, the 32‑ft dia­meter “secret wea­pons” carried a con­tainer of mag­ne­sium flash pow­der and 33‑lb high-explosive antipersonnel bombs.

Crude but ingen­ious, building a bal­loon that carried 1,000 lb of gear and that could sur­vive a 5,000‑mile trip across the Pacific Ocean, then auto­mat­ically drop its pay­load was tech­ni­cally chal­lenging. A hy­dro­gen bal­loon expands when warmed by the sun­light and rises, then con­tracts when cooled at night and falls. Japa­nese engi­neers devised a con­trol sys­tem driven by an alti­meter that dis­carded bal­last (sand­bags) or vented hydrogen to main­tain altitude (30,000–38,000 ft).

Some 285 to 300 Japa­nese fire bal­loons reportedly reached the North Amer­i­can conti­nent, some floating in­land as far as Mich­i­gan. Most of the fire bal­loons fell harm­lessly into the Pacific Ocean or self-de­structed before reaching the main­land. How­ever, pieces of paper from a Japa­nese fire bal­loon were found in a Los Angeles street. When the bal­loons were sighted near the West Coast or over land, air­craft from the U.S. Navy or U.S. Army Air Forces flew intercept missions to shoot them down.

The only known victims of one of these devices were six Ore­gon pic­nickers who were killed on May 5, 1945, when they tried to move a downed bal­loon and the anti­per­son­nel mine exploded. One bal­loon-caused brush fire trig­gered a shut­down of the Han­ford, Wash­ing­ton, atomic pro­cessing facil­ity, iron­i­cally delaying work on the pro­duc­tion of material for the atomic bomb that was later dropped on Nagasaki, Japan.

Following two news media accounts in early Janu­ary 1945 of a “bal­loon mystery,” the U.S. Office of Censor­ship enforced a news black­out on the sub­ject to reduce the chance of panic among West Coast resi­dents and to deny the Japa­nese any infor­ma­tion on the suc­cess of their launches. Dis­couraged by the appar­ent failure of their effort, the Japanese halted their balloon attacks in April 1945.

Japan’s Fire Balloon Campaign and Other West Coast Attacks

Japanese fire balloon bombCaptured Japanese fire balloon re-inflated for U.S. training demo

Left: A Japanese balloon bomb reportedly discovered and photo­graphed by the U.S. Navy in Japan. Large indoor spaces such as sumo halls, sound stages, theaters, and air­craft hangers were required for bal­loon assem­bly. The fire­bombing of Japa­nese cities by U.S. B 29 four-engine bombers destroyed two of the three hydro­gen plants needed by the pro­ject. Despite the initial high hopes of their designers, the Japa­nese fire bal­loon cam­paign was totally ineffective and survives in memory only as an ingenious curiosity.

Right: A Japanese fire balloon of mulberry paper (“washi”) re-inflated at the naval air station, Moffett Field, Cali­for­nia, after it had been shot down by a U.S. Navy plane on Janu­ary 10, 1945. The bal­loon is now owned by the National Air and Space Museum. Fire bal­loons were the first-ever wea­pon capable of inter­con­ti­nental range (a record not broken for decades), and their enve­lopes and appara­tus were found on the U.S. West Coast (Alaska, Wash­ing­ton, Ore­gon, and Cali­for­nia); in the Moun­tain states (Ari­zona, Nevada, Idaho, Mon­tana, Utah, Wyo­ming, and Colo­rado); and in the Mid­west (Texas, Kansas, Nebraska, North and South Dakota, Michi­gan, and Iowa). A few bal­loons landed in Mexico and Canada (Mani­toba, Alberta, Saskatchewan, Northwest Territories, and the Yukon).

Shoot-down of Japanese fire balloon, 1945alt_title

Left: Gun cameras capture Japanese fire balloons being shot down by a Lock­heed P 38 Light­ning near Attu in Alaska’s Aleu­tian Island chain, April 11, 1945. Fire bal­loons flew very high and sur­prisingly fast, and U.S. air­craft destroyed fewer than 20. Between 285 and 300 fire bal­loons reportedly landed in the U.S. Oregon recorded the most inci­dents, 45. British Colum­bia recorded 57. The last balloon found was in Alaska in 1955, its pay­load still lethal after 10 years. Japanese war­time propa­ganda announced fire bal­loons had wreaked havoc to forests, cities, and farm­land, inflicted casu­al­ties as high as 10,000, and described an Amer­i­can pub­lic in panic. The truth was, the six pic­nickers killed in Ore­gon (one preg­nant woman and five chil­dren) and the one fire­fighter were the only fatalities caused by Japan’s fire balloon campaign.

Right: The Japanese performed a small number of non-balloon attacks on the U.S. main­land throughout the war. In Febru­ary 1942 Japa­nese sub­ma­rine I 17 shelled an oil field up the beach from Santa Bar­bara, Cali­for­nia, and damaged a pump house. Later that June sub­ma­rine I 25 shelled a coastal fort, Fort Stevens in Ore­gon, churning up a swamp and a base­ball field (photo shows sol­diers in­specting the shell crater). Twice in September I 25’s crew assembled and launched a small floatplane that dropped a total of four incen­diary bombs, again in Oregon, starting a few small forest fires. U.S. Forest Service person­nel inves­ti­gated the origin of the fires, thinking they had been caused by lightning; how­ever, at the scene they found a crater, shrap­nel, and the bomb’s nose cone with Japa­nese markings. The bombing is not­able for being the only aerial bom­bard­ment of the contiguous United States by an Axis power.

Japanese Balloon Bombs Land in U.S. and Canada, November 1944 to April 1945