Ichinomiya Fu-Go Balloon Bomb Launch Base Site

The Ichinomiya Balloon Bomb Launch Base (一宮打上基地) was one of three coastal launch sites established along the Pacific shore of eastern Honshu for Operation Fu-Go (ふ号作戦) — Imperial Japan's ambitious and unprecedented campaign to attack the North American mainland using unmanned hydrogen-filled balloon bombs carried across the Pacific by the jet stream.

Located on the coast of Ichinomiya Town (一宮町) in Chiba Prefecture's Chosei District, the base served as the headquarters of the Second Battalion (第二大隊), comprising approximately 700 men organized into three squadrons operating six launch stations (Japanese accounts differ on the details, some giving two companies and about twelve launch pads). The other two bases were at Otsu in Ibaraki Prefecture (First Battalion, regimental headquarters) and Nakoso in Fukushima Prefecture (Third Battalion). Unlike Otsu, which had its own hydrogen generation plant, the Ichinomiya base relied on hydrogen gas manufactured at factories near Tokyo and transported to the site. A rail spur line was constructed from Kazusa-Ichinomiya Station (上総一ノ宮駅) to facilitate the transport of materials and hydrogen cylinders to the launch area.

The Fu-Go balloon bomb (風船爆弾, fūsen bakudan) itself was a remarkable if desperate weapon. Each balloon measured approximately 10 meters in diameter, constructed from multiple layers of washi (traditional Japanese paper made from mulberry bark) laminated with konnyaku (konjac) paste for gas-tightness. Filled with hydrogen, each balloon carried a payload of one 15 kg antipersonnel bomb and two to four 5 kg incendiary devices, along with an ingenious barometric altitude-control mechanism using sandbag ballast. Filling a single balloon required about 50 hydrogen cylinders (roughly 300 cubic meters of gas) and took several hours, limiting each launch station to four or five balloons per day.

Ichinomiya also played a key role in the development phase. In early 1944, large-scale experimental launches of approximately 200 balloons were conducted from Ichinomiya Beach to test the weapon system before operational deployment began in November. The campaign ran from November 3, 1944, through early April 1945, with the three bases collectively releasing approximately 9,300 balloons during the winter months when the jet stream was strongest. An estimated 300 reached North America, landing in locations across 26 U.S. states, Alaska, Canada, and Mexico. On May 5, 1945, a balloon bomb killed six civilians near Bly, Oregon — the only enemy-caused casualties on the U.S. mainland during the war.

After the war ended, the Japanese military systematically destroyed the Ichinomiya base, leaving no physical traces of the original launch infrastructure. The concrete launch pads that once dotted the beach have disappeared entirely. The town of Ichinomiya has put up an informational panel (解説板) marking the "balloon bomb launch base site"; it stands in a corner of a small park somewhat inland from the actual launch area. The marker serves as the sole physical commemoration of the site's wartime history.