Image credit: Southern Oregon Visitors Association

In November 1944, fifty years before Predator drones swept on the scene, the Japanese military devised a low-tech method of dropping bombs on foreign soil that didn’t require pilots. All it took was balloons—specifically, 9,000 33-foot-diameter “balloon bombs,” or Fu-Gos, each carrying 35 pounds of explosives.

Released from Japanese shores, these balloons were designed to rise to 30,000 feet then ride the jet stream east, making their way toward the U.S. in about three days. At that point, an altimeter would trigger a reaction that would jettison the bombs, which would explode once they landed, whipping up fires and panic across the country.

That, at least, was the plan. The Japanese would soon learn that you should never place your hopes of winning a war in the hands of the wind. Only a few hundred of these balloons made it to the States, and even fewer exploded. Plus, apparently the Japanese hadn’t checked the weather: The balloons landed during a cold, damp winter, sparking only a few brush fires that didn’t do much damage. One balloon landing in Nevada was picked up by cowboys and turned into a hay tarp. In Montana, two lumberjacks stumbled across a balloon with Japanese markings and the undetonated bomb still attached. Seven fire balloons in total were turned in to the Army, and as sightings continued to pop up everywhere from Alaska to Texas to Iowa, Americans started wondering what was up.

In January 1945, Newsweek ran an article titled "Balloon Mystery." At that point, the U.S. Office of Censorship stepped in, asking that media outlets refrain from mentioning the balloons, lest this give the Japanese the impression their attack had been a success, which might encourage them to send more. So the media kept their mouths shut. The Japanese, figuring there was no way Americans could keep this big a secret, were forced to conclude that their balloons had failed, and discontinued their use. Nonetheless, Japanese propaganda broadcasts boasted that their balloons had caused huge fires, widespread mayhem, and death counts as high as 10,000.

Only one balloon bomb claimed any American lives, and it was more of a sad tragedy than a military triumph: Five kids and their pregnant Sunday school teacher, Elyse Mitchell, came across the balloon in Oregon during a picnic in the woods. As Mitchell’s husband explained, "[One of the kids] came over and told us that there was a white object near by. We went to investigate. It blew up and killed them all." Mrs. Mitchell, Joan Patzke (11), Dick Patzke (13), Eddie Engen (13), Jay Gifford (12), and Sherman Shoemaker (12) became the only World War II casualties in the continental U.S., although they were hardly the sort of PR coup that would buoy Japanese spirits.

After their death, the media blackout was lifted to make Americans aware of the threat. Parks were filled with posters depicting what the balloons looked like, and warnings to not mess with them.

At the end of the day, Japan’s balloon bombs boasted a kill rate of only .067 percent. It was a flop as far as secret weapons go, although the Japanese get points for creativity. And remnants of these balloon bombs still exist, with parts being found as recently as 1992. So if you spot a balloon in the woods, steer clear—and take a moment to appreciate the fact that you may be witnessing one of the best-kept secrets of World War II.

Also...

This wasn't the only attack on Oregon during World War II. In 1942 a Japanese pilot in a submarine-based floatplane tried to drop incendiary devices over the forests around the town of Brookings.

In 1988 the Chicago Tribune caught up with the pilot of that mission, Nobuo Fujita, who returned to Brookings several times after the war and became something of an honorary citizen. According to his 1997 New York Times obituary, he gave the local library $1,000 to buy books about Japan for children, "so that there wouldn't be another war" between the two countries.

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As for Elyse Mitchell's husband, life was marred by another tragedy. After his wife's death, he remarried, became a missionary, and traveled to Vietnam. In 1962 he was taken captive by the Viet Cong and never heard from again.

Judy Dutton is a regular contributor to mental_floss magazine. For our current issue, she wrote "9 Weapons That Failed Spectacularly (and 1 That Possibly Didn't)."