Fu-Go Balloon Bomb

The Fu-Go was a Japanese incendiary weapon built around a hydrogen-filled paper balloon 33 feet (10 meters) across, carrying four 11-pound incendiary bombs and one 33-pound high-explosive anti-personnel bomb. It was developed by Japan's Imperial Army at the Noborito Research Institute, also called the Ninth Technical Research Institute, and used an automatic altitude-control system to ride the jet stream roughly 6,000 miles across the Pacific Ocean toward North America. Around 9,300 balloons were launched from the coast of Honshu between November 1944 and April 1945, intended to start large forest fires and spread panic, though the campaign was aimed chiefly at home propaganda and the military itself had little confidence in its practical effectiveness.