Japan’s Ultra Secret World War II Super Weapon: Balloons

  • The world’s first intercontinental weapons system (meaning that it was a weapon that could be launched from one continent and reach another) was first used in World War II. This weapon system carried its payload for over 5,000 miles (8,000 km). This would be the world record for nearly 50 years. You might think that either America or Germany was behind this. But you would be wrong. The creators of this most interesting of weapons are the Japanese military. What was this record-setting weapon? Big balloons.

    Fire Balloons

    I remember as a child going to the bank with my mom, I would always pester the bank clerk for a balloon. I was most excited when I could get one that was full of helium, but eventually, the most tragic of occurrences would happen – I would accidentally lose my grip on the string and have to helplessly watch as the balloon floated away high in the sky. A young Japanese scientist, Sueyoshi Kusaba, must have had a similar experience, and instead of crying to his mom to try to get another one, he must have thought, “Maybe I can make that a weapon.”

    Sueyoshi Kusaba was in charge of the Ninth Armies’ Number Nine Research Laboratory. In the ending days of the Pacific War, Japan was absolutely desperate to find any solution to their current dilemma. They needed to find some way to put pressure on America. He and his team came up with one of the most interesting weapon designs I have ever heard of. Strap a bunch of boys to big balloons and have the balloons cross the pacific to America.

    How Did It Work

    The fire balloons, or “fusen bakudan” (風船爆弾) in Japanese, seem like a crazy idea, but the science behind it was all very sound. The balloons were cheap and easy to produce and were nearly impossible to find. Japanese scientists learned that the Pacific jet stream could carry the balloons from Japan to America in 3 days.

    The fire balloons were a work of engineering genius. Laboratory Nine set up the balloons so that as the hydrogen in the balloons began to run out over time, lowering the balloons altitude, and the bombs would drop themselves automatically. They did this by calculating the rate that hydrogen is lost, and then putting in an exact amount of hydrogen in the balloons so that the balloons would drop to a certain altitude which would trigger an 84-minute fuse that would drop the bombs. It sounds like a contraption from that old board game Mouse Trap, but the control system itself worked incredibly well. Kusaba and his men would launch over 9,000 of these deadly balloons into the midsts of the unsuspecting Americans.

    How Effective Was It

    Well here’s the rub. As cool and interesting as the idea was, it was nearly completely ineffective. If you have ever traveled around in America you might have realized something – America is really big! There are incredibly vast stretches of emptiness between cities and towns. You can literally drive for hours in America and not see anything but plains, mountains, and clear horizons all around you. So most of these bombs dropped on to big patches of nothing.

    Of the 9,000 that were launched, only one caused any casualties. On May 5th of 1945, a pregnant woman, Elise Mitchell, was killed along with 5 children in Southern Oregon. They were killed when one of the balloons descended near them, and they went to see what it was when it exploded.

    There was one incredibly close call that one of the balloons made it all the way to the Manhattan Project’s main production base, which caused an electrical short to the nuclear power’s reactor. A second generator kicked on almost instantly. But had the attack been more successful, it could have crippled the entire Manhattan Project causing America to be unable to complete the nuclear bomb.


    While the fire balloons were not successful by any traditional measure, they did strike an incredible amount of fear into the American populace. Imagine death falling from the sky, and there is nothing to stop it from getting to you. This would be a level of fear that America had never before experienced and would not experience again until the darkest days of the Cold War. These balloons also show a level of ingenuity that many often forget Japan has in spades. It might seem really funny, but balloons can be deadly weapons!

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