On May 5, 1945, Reverend Archie Mitchell took his five-month pregnant wife and a group of five children from the church, where he was the pastor, for picnic and fishing up in the mountains near Bly in Oregon. Mitchell dropped the group near a logging road so that they could hike through the woods while he drove up the mountain. The picnickers eventually arrived at Leonard Creek, where they intended to lunch. While Mitchell was unloading the vehicle, he heard one of the children say, “Look at what we’ve found! It looks like some kind of balloon.” Archie Mitchell’s wife, Elise, and the children ran to see what had been found. Moments later, an explosion ripped through the mountain stillness, instantly killing Elsie Mitchell along with Sherman Shoemaker, Edward Engen, Jay Gifford, Joan Patzke,and Dick Patzke, all aged between 11 and 14 years old. These were the only people killed by enemy attack on American soil in the Second World War.

A tree snags a balloon bomb in Kansas on Feb. 23, 1945. Photo credit: Japan Times

What Archie Mitchell’s wife and the children discovered that day was a Japanese balloon bomb or “fire balloon” that had flown 8,000 km across the Pacific and landed on Gearheart mountain, where it lay dormant until the victims inadvertently set it off. A bomb disposal expert later guessed that the bomb had been kicked.

The Japanese balloon bomb was a brilliant invention built to offset the loss of Japanese air power during the war in the Pacific. The Japanese did not have a long range and heavy bomber like the B-29 that could level American cities, nor did it have enough aircraft carriers to transport what few aircrafts they had across the ocean. So the Japanese devised a new way of attacking the enemy.

Two decades earlier, a Japanese meteorologist named Wasaburo Oishi discovered a stream of high-altitude current, now known as the jet stream, blowing across the Pacific. Oishi conducted a series of experiments with pilot balloons launched from various locations in Japan, and successfully established the presence of these persistently strong air currents blowing from the west to the east. Unfortunately, Oishi chose to publish his work in Esperanto, an “artificial” language few spoke, thereby dooming his work to international obscurity. When the Japanese military got hold of his papers, they realized that this high-altitude air currents could be used as a conveyor belt to carry bombs and terror across the Pacific to the United States.

Over a five month period ending in April 1945, the Japanese launched over 9,000 fire balloons. Each hydrogen-filled balloon was up to 10 meters wide and carried several hundred pounds of incendiary and high-explosives. The balloons were allowed to rise to 30,000 feet before a control mechanism kicked and kept the balloons in the right altitude by discarding sandbags when it dropped too low or venting hydrogen when it rose too high. For three days the balloons drifted across the Pacific riding the high altitude jet streams. On the third day a timing mechanism released the bombs over the US, and the balloon was self-destructed to prevent the enemy from reverse-engineering the technology.

Of the 9,000 launched, some 300 of them reached the western coast of the North American continent, from Alaska to Mexico, and as far inland as Texas, Wyoming and Michigan. Most fell remotely and harmlessly in uninhabited locations causing little to no damage, although it did cause some amount of concern, the biggest of which was that of wildfire. Some 2,700 troops were stationed at critical points along the Pacific coastal forests with fire-fighting equipment. Fighter aircrafts scrambled to intercept the balloons, but they flew so high and so incredibly fast that fewer than 20 were shot down.

A balloon bomb 'chandelier' is displayed at the Canadian War Museum in Ottawa.

In the beginning nobody believed that the balloons could have come directly from Japan. But when the sand from the sandbags were analyzed for its mineral composition and the types of diatoms and other microscopic sea creatures in them, it left little room for doubt. Geologists eventually tracked the sand down to a beach near the city of Ichinomiya, on the island of Honshu. Aerial reconnaissance soon found what there looking for—two hydrogen production plants nearby, which were immediately destroyed by bombing.

The American government did everything they could to keep fire balloons out of the media, to deny the Japanese valuable intelligence of the balloon bombs effectiveness. They also didn’t want the American public to panic.

Meanwhile Japanese authorities reported that the bombs were hitting key targets, and thousands were dead or injured to help sustain morale on the home front in Japan, but deep down they knew the balloon bombs were a fiasco. Besides, with two of the key hydrogen plants now gone, General Kusaba ordered the operation to cease.

It was only after the death of the picnickers in Oregon that the press blackout was lifted when authorities realized that public knowledge of the threat could have possibly prevented the tragedy.

Today there is a small picnic area at the site where the fire balloon exploded killing six people. A stone monument with a bronze plaque lists the name of and ages of the victims. Adjacent to the monument is a ponderosa pine still bearing scars from the explosion.

The monument at Mitchell Recreation Area. Photo credit: Jayedgerton/Wikimedia

The remains of a balloon bomb that exploded on a farm in North Dakota in August 1945.