Fu-Go Balloon Bomb Campaign

The balloon bomb was developed by the Army's Noborito Research Institute (Ninth Army Technical Research Institute) with the help of meteorologists who had studied the strong winter westerlies at high altitude. The standard Type A balloon was about ten metres in diameter, made of layers of Japanese paper (washi) glued with konnyaku paste, and carried incendiary and high-explosive bombs with an automatic ballast-dropping altitude control.

The envelopes were made largely by mobilised schoolgirls, working in factories and in large halls such as the Nichigeki theatre and the Kokugikan in Tokyo. Launching was carried out by a special balloon regiment from Otsu in Ibaraki Prefecture, Ichinomiya in Chiba Prefecture and Nakoso in Fukushima Prefecture, beginning in November 1944 and ending in April 1945.

Of about 9,300 balloons released, some 285 incidents were recorded in North America at the time and it is estimated that around 1,000 may have reached the continent. Physical damage was slight. On 5 May 1945 a woman and five children on a church outing were killed near Bly, Oregon, when they found a grounded balloon; these were the only deaths from enemy action on the US mainland during the war. A balloon also briefly cut power to the Hanford plutonium works. US authorities restricted news of the balloons to deny Japan information on results.

The use of biological agents was studied at Noborito but was not carried out. The campaign is documented at the Meiji University museum on the former Noborito site and at monuments at the launch sites.