The children thought they had found a deflated weather balloon tangled in the Oregon pines; they had thirty seconds to live.

The Day Idaho's Skies Turned to Ash: Operation Firefly's Secret War

When the Japanese Empire Sent 9,000 Balloon Bombs to Burn America

Japan's secret balloon bomb campaign killed six American civilians and nearly disrupted the Manhattan Project.

On the morning of July 3, 1945, Archie Mitchell drove his pregnant wife Elsie and five Sunday school children into the pine forests near Bly, Oregon, for a picnic. While Mitchell parked the car, the children discovered something strange in the underbrush—a deflated paper balloon tangled in the trees, attached to what looked like a cluster of sandbags.

Elsie called out to her husband. Then the forest exploded.

The six civilians—five children between ages 11 and 14, and one pregnant woman—became the only people killed by enemy action on the continental United States during World War II. They had stumbled upon one of Japan's most audacious and least-known weapons: the Fu-Go balloon bomb.

Beginning in November 1944, the Japanese military had launched an estimated 9,300 hydrogen-filled balloons from beaches along Honshu. Each balloon, 33 feet in diameter and constructed from mulberry paper glued together by schoolgirls, carried incendiary devices and anti-personnel bombs. They rode the newly-discovered jet stream across 5,000 miles of Pacific Ocean, timing mechanisms dropping sandbag ballast to maintain altitude, until they descended over North American forests.

💡 The balloon bombs were assembled by Japanese schoolgirls who were told they were making weather balloons—many only learned the truth decades later and expressed profound grief upon discovering their handiwork had killed children.