“For months the War Department knew that the continent’s airspace was being invaded regularly by strange automated bomb-dropping balloons – they just weren’t reporting it.”

TO THOSE ENJOYING lunch in an idyllic picnic ground in Bly, Oregon on the morning of May 5, 1945, the horror of the Second World War must have seemed a world away. But for a 26-year-old Sunday school teacher named Elise Mitchell and five of her pupils, that was about to change.

While playing in the park, the group stumbled upon what appeared to be an enormous deflated weather balloon lying in a clearing. As the youngsters and their guardian approached the strange object, a 33-lb. bomb tethered to underside of the limp canopy suddenly exploded. The blast killed all of them instantly.

While news of the tragedy rocked America, it hardly surprised the U.S. military. For months the War Department knew that the continent’s airspace was being invaded regularly by strange automated bomb-dropping balloons – they just weren’t reporting it.

Japan’s Balloon Bombs

As far back as the fall of 1944, authorities in both Canada and the United States were picking up reports of mysterious explosions from the interior of British Columbia south to the Mexican border. Military pilots on ferry and training runs were radioing in sightings of unidentified high-flying balloons drifting eastwards on fast air currents. A number of patrol planes had even pursued and attack the invaders (as many as 20 had been engaged), however most were drifting too high to reach. During the same period, remnants of balloon canopies were being recovered all over the western United States and Canada.

At first, both governments pressured the news media to suppress the stories, partly to avoid setting off a panic, but more to deprive the enemy details about the effectiveness of the weapons.

While Allied planners knew that the devices carried both anti-personal bombs and incendiary explosives, the precise origin of the dangerous invaders still remained a mystery. Were they being sent aloft by German or Japanese spies operating within the U.S.? Were they coming from ships or submarines cruising off the coast? Some even hypothesized that inmates in Allied POW camps inside North America were somehow launching the weapons secretly. Only later did it emerge that the balloons were in fact coming from Japanese home islands half a world away.

“Fu Go”

Conceived by the Japanese army as a terror weapon, the 30-foot wide, hydrogen-filled balloons were designed to travel across the Pacific and over North American airspace where they would randomly drop bombs onto cities or the countryside. Although Tokyo never believed the balloon bombers, dubbed Fu Gos, would win the war, they were seen as an inexpensive way to put a dent in American morale.

The balloons were initially constructed using a silk and rubber compound. Later, when raw materials became scarce, heavy-duty paper was substituted. Each device was equipped with a 30-pound anti-personnel bomb or a 26-pound incendiary charge, as well as an altimeter, some simple controls, and several hundred pounds of ballast.

Once launched, the balloons would rise to an altitude of more than 30,000 feet (9 km), at which point they would float into the jet stream and hurtle eastwards on the massive air current at speeds of up to 100 mph (160 km/h). A rudimentary venting system would release hydrogen if the balloon rose above 39,000 ft. while ballast would be jettisoned automatically if it dipped below 30,000 ft. After three days aloft, the balloons would more than likely be over North America, at which point a mechanism would release the explosives. Once empty, the balloon would self-destruct by way of a small explosive charge.

From the fall of 1944 and April of 1945, more than 9,000 of the balloons were released. Only about 10 percent were estimated to have actually reached Canada or the United States. Most of those released their payloads over the coastal states; some penetrating as far as Kansas, Iowa and even Michigan.

While the six fatalities at Bly, Oregon would be the only civilian victims of the balloons, one descended onto a power line near the Manhattan Project’s Hanford Works in Washington State causing a temporary power fluctuation there. Another is suspected to have caused a forest fire that claimed the lives of two soldiers.

The balloon that exploded in Bly finally forced the government to confirm that North America was under attack. Ironically, it was one of the last ever launched; Japan had already chosen to abandon the project.

Despite the ineffectiveness of the campaign, the attacks caused considerable consternation in Washington where it was feared that the next wave of the weapons might be equipped with chemical or biological agents.

There were 300 confirmed sightings of bomber balloons in the six months of the program, however canopies and debris turned up in remote areas for years after the war, the last being recovered in the Pacific Northwest as late as 1978.

Operation Outward

It would be a mistake to think that the Japanese were the only military power to use weaponized balloons in World War Two. Between 1942 and 1944, Great Britain unleashed more than 99,000 of them on Germany. While 53,000 of these carried 6 lb. incendiary bombs, the rest held no explosives at all. Instead they trailed a 270-foot long strand of steel piano wire that was designed to hang low and short out high voltage power lines. The British came up with the idea in 1940 when a freak storm scattered a cluster of barrage balloons, some of which were blown across the North Sea to Scandinavia where their mooring cables played havoc with power lines. Shortly after the incident, the Royal Navy advanced the idea of releasing thousands of similar balloons over Germany. The plan was called Operation Outward. The 10-foot wide balloons, each worth only 35 shillings a piece, were designed to drift semi-inflated over Germany, at which point they would automatically fill with gas and drift upwards of 16,000 feet and then gradually descend. Automatic timers and fuses would fire that would to either unspool the steel wire or drop explosives.

Almost immediately, the balloons got results – forest fires near Berlin and in eastern Germany were reported only days after the first release in March, 1942. Four months later one of the balloons collided with power lines causing a chain reaction that destroyed an electrical station near Leipzig. Soon, Luftwaffe aircraft were scrambling across occupied Europe to intercept the balloons, which cost the Axis precious fuel. At the peak of the campaign, as many as 1,000 balloons were being launched simultaneously from two sites – one near Dover the other up the coast at Felixstowe. Almost all of the 140 personnel associated with the program were from the Women’s Royal Navy Service (WRNS).

Project E77

The American military briefly explored the idea of balloon bombs also, although not during World War Two, but rather the Cold War. In 1951, the Chemical Corps of the U.S. Army began testing hydrogen-filled high altitude balloons (codenamed E77s) as a method of secretly dispersing biological agents designed to wipe out Soviet or Chinese agriculture. Wheat destroying fungi were packed in a small two-foot canister suspended beneath the balloon. Once over enemy territory, the container would automatically open and disperse feathers that were treated with spores that cause ‘stem rust’ – a fast-spreading disease that can ravage vast regions of cereal crops. During the 1950s, the U.S. military planned to disperse between 15 and 20 percent of all biological agents via balloon bombs. Although, tested for nearly a decade at a military preserve in California, no E77 balloon was ever released. By 1960, the E77 program was suspended. Subsequent biological weapons were instead designed to be delivered by bombs via aircraft.