During the Second World War, it became clear that when it comes to implementing plans to kill the enemy, humans are by far the best-equipped animals. One of the most interesting examples is the balloon-bombs manufactured by Japan in the final years of the conflict.
As early as 1932, a Japanese scientist named Nakayama, working at the Central Meteorological Observatory in Takao, Formosa, had discovered an air current that flowed at high altitude between the Japanese islands and the west coast of North America. Called the Jet Stream, it was nothing more than a curiosity until ten years later, when another Japanese scientist, Dr. Fujiwara, realized that this current could be used with good chances of success to send explosives to their enemies in the United States.
Naturally, at that time it was not easy to build a device that could fly thousands of kilometers and hit its target. It would be decades before the GPS system would even be conceived, and raw materials in Japan in 1940 were hardly abundant. In this context, Fujiwara began to devise a “home-delivery bomb system” that would be viable and cheap. After thoroughly studying the characteristics of the Jet Stream and how it behaved throughout the year, he knew that a suitably equipped balloon could cross the ocean and crash into the United States.
He quickly wrote a letter to the military leadership of his country, explaining that “during the summer, when the Jet Stream is of low intensity, a balloon could traverse the Pacific in a week or ten days. The number of balloons that would reach their target,” Fujiwara clarified, “would be approximately 20 percent of those launched.” This was not a problem because the cost of each balloon was not too high, and they could be built in large quantities. “In winter,” the letter continued, “the trip would not last more than two or three days, and between 60 and 70 percent of the balloons launched would reach their target.”
The Balloon Project
Everything seemed to indicate that winter was the best time to attack, but Fujiwara also knew that cold and snow would prevent an incendiary bomb from being effective enough. That is why in his letter he concluded that “it is very impractical to launch during autumn and spring.” The plan was approved by the military, and quickly they began to manufacture two models of balloons: Type ‘A’ was made by the Army and Type ‘B’ by the Navy. They differed in only a couple of details, and by the end of the war about 9,000 Type ‘A’ and 300 Type ‘B’ balloons had been built.
Both balloons had a diameter of about ten meters and were made of several layers of parchment glued together with “konnyaku”, a gelatinous paste used in Japanese cooking. Incredibly, this material of dubious quality proved to be much more effective at retaining hydrogen inside the balloon than the best fabrics produced by Western industry of the time. Once launched, the balloons traveled over the ocean at altitudes between 9,000 and 11,000 meters, where thanks to the air current discovered by Nakayama they reached an average speed of about 30 kilometers per hour. They carried a device based on a barometer that released ballast—about 30 sand-filled balls—when the balloon descended below 9,300 meters, and opened a valve that allowed some hydrogen to escape when it exceeded 11,000 meters.
The destructive action was carried out by three or four fragmentation bombs of 15 kilograms each and an incendiary bomb that traveled in the gondola. A mechanism released them after all the sand bags had been dropped, and another caused the balloon to explode after the bombs were released. Some balloons, used as guides, even carried a device that emitted radio signals to indicate to the base in Japan whether the route they were following was correct. The idea was that no trace of the vehicle that had carried out the bombing would remain, but the failure of this self-destruction mechanism in several balloons allowed American military to discover what was happening.
The Discovery and Its Aftermath
On November 4, 1944, a United States Navy ship found floating in the Pacific Ocean, near the coast, a large piece of torn cloth. When they tried to bring it aboard, they noticed that a fairly heavy load was attached to the cloth, but it came loose and sank to the bottom when they were hoisting the whole thing with a crane. They quickly discovered that it was part of a balloon, and some inscriptions in Japanese served to deduce that a new form of attack was taking place.
Without wasting time, they informed General Wilbur of the US Army, and along with the remains of another balloon found also in the sea and another that appeared burned in Montana, the American military was able to glimpse the danger these devices posed: a large-scale aerial attack with balloons could not be ruled out. In the following weeks, the remains of another two hundred balloons were found in the northwest Pacific and in Canada. Pieces of cloth belonging to another seventy-five were found in other regions, in ocean waters or even in northern Mexico. Flashes seen in the sky during the night served to determine that at least a hundred more had exploded in the air.
Although so far the explosives had not caused any casualties—fortunately they had all fallen in unpopulated areas or in the ocean—General Wilbur requested that their existence be kept secret, to avoid worrying citizens and so that the Japanese high command would not know whether their plan had succeeded or not. Meanwhile, American geologists carefully studied the sand contained in the ballast bags and found five sites—all in Japan—from which it came. The Air Force photographed those areas, and in one of them they found a large factory surrounded by gray spheres, which were undoubtedly balloons ready to begin their journey. However, shortly after, the balloons stopped arriving in the United States.
As was learned after the war, the Japanese generals considered that they were wasting hydrogen and other scarce materials without obtaining concrete results. This last point was not exactly true, but the silence of the American press was decisive in making the Japanese high command believe it. In reality, a group of children on a field trip found one of the fallen balloons, and when they tried to drag it they caused the bombs to explode, killing five of them and a woman, but the news was never published.
What would have happened if instead of bombs, the balloons had been loaded with biological agents? Surely the Japanese plan would have wreaked havoc in the United States. However, and despite the fact that the Americans themselves feared this possibility, this never happened. The tactic devised by Fujiwara allowed bombing the American continent from Japan, but a couple of small details prevented it from becoming a complete success. Didn't you know?
https://old.neoteo.com/el-escuadron-731-1932/
