balloon bombs

balloon bombs, balloons with explosive and/or incendiary devices suspended beneath them. The British experimented with them in 1939, but an attempt to dispatch incendiary versions to set the Black Forest alight—the Germans were short of timber—ignited only an East Anglian plantation when the wind changed. Later in the war the Japanese employed them on a fairly large scale with only marginally greater success. The ones they used were nearly 28 m. (91 ft.) round and made of bonded mulberry paper, and thousands of them were released between November 1944 and March 1945 in the hope that the prevailing winds would carry them to the USA. They were kept at the optimum height by a mechanism which, if the balloon went too high or too low, released helium from the sac or jettisoned a sandbag. About 200 landed in Mexico and Canada, as well as in Alaska and other parts of the USA, and it was initially feared they carried deadly bacteria as part of a Japanese biological warfare campaign. One killed a woman in Helena, Montana; another killed six people in Oregon; otherwise they did little material harm. See also bombs.