An excellent article by J.R. Schrock in the American Entomologist (Winter 2023) reveals more about the insane plans of Shiro Ishii (1892-1959) at the head of Unit 731, Japan’s experimental center for biological warfare. This center committed unspeakable atrocities from 1932 to the end of the Second World War.
What are we talking about?
In 1925, Japan was one of the 38 signatories of the Geneva Protocol banning biological weapons. This reinforced the belief of the young physician Shiro Ishii (see illustration) that these weapons must have special properties, otherwise they would not have been banned by the League of Nations! He then obtained support for his biological weapons project from the military hierarchy.
The first experiments
The first results on animals enabled him to develop ways of spreading outbreaks; due to containment problems and ethical constraints, he was unable to carry out human experimentation in his Tokyo laboratory.
In 1932, the Imperial Japanese Army invaded Manchuria, and Ishii took advantage of the situation to move his laboratory near Harbin in occupied Manchuria, where the common man could be used for human testing. The area was too densely populated and the laboratory was not very discreet: Ishii moved it 100 km to the south, to the fortress of Zhongma. This is where the small village of Beiyinhe was located, and was forcibly evacuated. The village was then completely razed: prison cells and medical laboratories were built by Chinese workers, who were then killed to conceal the function of the newly constructed fortress.
As some prisoners managed to escape, they risked revealing the nature of the research carried out at Zhongma Fortress, and it was closed in 1937. Ishii’s activities were transferred to an even larger facility, built at Pingfang in 1938, 33 kilometers south of Harbin. It was here that it took the name “Unit 731”.
Meanwhile, Japan’s military leaders were increasingly convinced that biological weapons could be effective, even essential, against a possible invasion by Soviet forces from Siberia.
Cholera
Over 30 pathogens were studied for military use, including cholera, anthrax, typhoid, bubonic plague and typhus. Unit 731 cultivated large quantities of cholera bacteria (Vibrio cholerae), a water-borne disease that causes death through diarrhea and dehydration. Japanese soldiers released these cultures into a river intending to infect civilians and enemy troops in towns downstream.
Japanese soldiers who dispersed the causative agent contracted cholera, while the impact on the enemy and civilian population downstream was slight. Ishii discovered that the environment diluted and killed the bacteria too quickly. He needed a way for his pathogens to survive and find their human targets. He turned his attention to insect-borne diseases: flea-borne bubonic plague and louse-borne typhus. He wanted to enlist insects in the war. Let’s not forget that we’ve already touched on the problem of insects used in biological weapons.
Plague and typhus
The experiments
Ishii’s teams have worked on cultivating the most virulent strains of plague using mouse and ground squirrel fleas. To cultivate the bacteria and inoculate the insects, Ishii even developed protective suits.
Infected fleas carrying bubonic plague and lice carrying typhus were mixed with sand and placed in a porcelain bomb.
These bombs were dropped from airplanes, exploding some 300-500 feet above the ground, and 80% of the insects survived the blast. To test the effectiveness of aerial dispersal, healthy prisoners were attached to crosses laid out in a large circular area (see illustration). An aerial bomb loaded with infected insects was loaded onto a plane and dropped over the target, exploding in mid-air. In a short space of time, the infected insects infected the attached prisoners, most of whom died within two to ten days.
By testing the virulence of bacterial strains on human victims, Ishii set a new standard for cruelty. As the bodies of bubonic plague victims decompose rapidly, his collaborators carried out “autopsies” while the victim was still alive, to assess organ damage before death, without anesthesia. These human victims were called “maruta”, which means “logs” in Japanese.
Over a hundred scientific articles have reported on these experiments, citing only Manchurian monkeys as subjects (there are no monkeys in Manchuria!). In most cases, the victims were people kidnapped off the streets.
In practice
The exact number of victims is unknown, but aerial bombardments of Chengde, Ningbo, and a dozen other Chinese cities claimed the lives of around 580,000 Chinese, ¾ of them by entomological weapons. Ishii continued his work and in 1944 began cultivating agricultural parasites to spread in enemy territory to destroy crops to cause famine. However, Japan was losing the war. Aware of the likely consequences of discovering Unit 731’s activities after Japan’s surrender on August 14, Ishii ordered Chinese workers to destroy Unit 731 and then executed them.
What has become of Shiro Ishii and the senior staff of Unit 731?
One might think that Ishii Shiro and the senior officers of Unit 731 would soon be tried for war crimes at the 1948 Tokyo International Military Tribunal, the Eastern equivalent of the Nuremberg Trials in Europe. However, they returned to Japan and were never tried as war criminals. American military investigations revealed the development of germ bombs and recommended an immunity agreement against information. At the time, the US was also interested in biological warfare. Fort Detrick personnel were eager to gain access to scientific data not available to the U.S. military.
American scientists readily accepted the Japanese scientists and their results because of their scruples about human experimentation.
Ishii Shiro finally died in his bed at the age of 67.
On the other hand, the Russian army captured 12 members of Unit 731 and put them on trial. The West then learned of criminal acts such as the dropping of plague-carrying microchips and inhumane experiments on prisoners. This event was considered propaganda at the time. However, the Russians also traded clemency for information. These 12 Japanese war criminals were finally released and repatriated to Japan in 1956.
Many of the Japanese doctors who took part in Unit 731’s monstrous autopsies went on to hold high office in Japan: governor of Tokyo, director of Japan’s largest pharmaceutical company, president of the Japanese Medical Association, etc. For almost 40 years, the activities of Unit 731 remained virtually unknown, until the publication in 1997 of a report entitled “Unit 731: Eyewitness Accounts” by Hal Gold. Other reports and publications followed, revealing the atrocities committed by Unit 731.
Conclusions
Harbin’s Unit 731 Museum displays documents and artifacts from this horrific period of war and issues a warning to all mankind. As one Japanese veteran said without remorse, “When you’re at war, you have to do whatever it takes to win.” The Unit 731 Museum in Harbin is here to help humanity avoid that path.
The author of this paper, an entomologist himself, concludes: if Robert Oppenheimer remarked, after the successful testing of the atomic bomb, that now “physicists have come to know sin”, it is at Pingfang, with the corpses and ashes of the victims of biological warfare experiments buried beneath the soil, that entomology has become diabolical.
Autor: Prof. François Renaud