The Buzz

Japan Might Have Invented the Ultimate Way to Kill an Aircraft Carrier

Plans to employ bioweapons cannot help but seem especially short-sighted given the indiscriminate and unpredictable nature of diseases. If the attack at Bataan had been carried out, for example, soon-to-be victorious Japanese troops would likely have fallen victim to their own plague. Just as air raids broadly targeting the civilian populations generally proved both cruel and of little military effectiveness during World War II, biological weapons were mostly “useful” for killing civilians. And if a bioweapon ever had proven successful in triggering a pandemic, such an outcome could have proven disastrous for both sides of the conflict.

During World War II, Japan infamously deployed biological weapons in attacks that infected and killed thousands of Chinese citizen. Less well known, however, is the fact that Japanese strategists also planned to deploy plague bombs against U.S. forces on at least four separate occasions—each only narrowly averted by circumstance. The last such attack, known as Operations Cherry Blossoms at Night, envisioned bombing San Diego with plague-infected fleas.

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The Japanese bioweapons program was the brainchild of Gen. Shirō Ishii, who in the 1930s received backing at the highest levels to form a biological warfare unit known as Unit 731, deceptively designated the “Epidemic Prevention and Water Purification Department” of the Kwantung Army deployed to China. Unit 731 established a massive 150-building complex in the Pingfang District of Harbin (then part of the puppet state of Manchuria), where it developed and tested its weapons on involuntary human subjects, around two-thirds of whom were Chinese, with most of the rest coming from the Soviet Union. Their subjects would later include a small number of Allied POWs, Koreans and Pacific islanders.

One cannot overstate the monstrousness of Unit 731’s testing program. Human beings were vivisected while still alive without anesthetic, or had major organs removed to see how long they would survive, then had their remains pickled in jars. Subjects had their limbs frozen until afflicted with frostbite, then had those limbs beaten with sticks or amputated. Others afflicted with syphilis, including children, were forced to have sex at gunpoint with other prisoners, and the progression of the disease was then observed. Live human beings were used in weapons tests of grenades, poison gas, flamethrowers and bombs—including air-dropped biological bombs carrying anthrax or fluid-form bacteria.

However, the chief weapon favored by Japanese biowarfare specialists appears to have been the plague, the bacterial infection which wiped out much of Europe’s population in the fourteenth century during the Black Death. A few days after infection, a plague-afflicted person may begin exhibiting symptoms, including grotesque buboes, high fever, gangrene in the extremities and chills or seizures, with a death rate of around 50 percent for untreated individuals.

Unit 731 was capable of producing around sixty pounds of plague agent in a few days, and the method of transmission mimicked that found in nature: plague-infested fleas. The fleas were stored in ceramic Uji-50 bombs with celluloid fins and dropped out of airplanes onto civilian communities. The released fleas went on to infest local rats, which in turn would contaminate food stores, spreading the plague to human beings.

This delivery mechanism was employed by Japanese bombers over the cities of Ningbo and Changde in China, and on some occasions proved “successful” in starting a plague, although whether casualties number in the hundreds or tens of thousands remains disputed. Following the Doolittle raid over Tokyo in 1942, Japanese troops launched a revenge campaign called Operation Sei-Go, which included the employment of cholera, typhoid, plague and dysentery bioweapons—which in addition to killing tens of thousands of Chinese, may have backfired and killed 1,700 Japanese troops by one estimate.

Having used China as a laboratory for its bioweapons, the Japanese military began searching for ways to use the weapons against its chief military threat. In March 1942, plans were made to drop 150 million infected fleas in ten separate plague-bomb attacks against U.S. and Philippine forces, who were fighting a desperate last stand on the swampy Bataan Peninsula of the Philippines. However, Allied forces surrendered that April, before the attack could be executed. That same year, Japanese military commanders mulled biological attacks on Dutch Harbor, Alaska; Calcutta, India; and parts of Australia, but didn’t carry them out. Other schemes proposed including infecting U.S. cattle and grain crops, or using balloon bombs as a means to disperse plague agents in North America.