Unit 731 (731 部隊 Nana-san-ichi butai?) was a covert biological and chemical warfare research and development unit of the Imperial Japanese Army that undertook lethal human experimentation during the Second Sino-Japanese War (1937–1945) and World War II. It was responsible for some of the most notorious war crimes carried out by Japanese personnel.
Officially known by the Imperial Japanese Army as the Kempeitai Political Department and Epidemic Prevention Research Laboratory, it was initially set up under the Kempeitai military police of the Empire of Japan to develop weapons of mass destruction for potential use against Chinese, and possibly Soviet forces.
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Unit 731 was based in the Pingfang district of the city of Harbin in the puppet state of Manchukuo.
More than ten thousand people,[1] from which around 600 every year were provided by the kempeitai,[2] were subjects of the experimentation conducted by Unit 731.
Those were both civilian and military of Chinese, Russian, American and other nationalities as well as some Japanese criminals from the Japanese mainlands.[3] The victims who died in the camp including at least 25 victims from the former Soviet Union, Mongolia and Korea. [4]Some American and European Allied prisoners of war also died at the hands of Unit 731.[4]
According to the 2002 International Symposium on the Crimes of Bacteriological Warfare, the number of people killed by the Imperial Japanese Army germ warfare and human experiments is around 580,000. [5] According to other sources, the use of biological weapons researched in Unit 731's bioweapons and chemical weapons programs resulted in possibly as many as 200,000 deaths of military and civilian in China .[6]
Unit 731 was the headquarters of many subsidiary units used by the Japanese to research biological warfare; other units included Unit 516 (Qiqihar), Unit 543 (Hailar), Unit 773 (Songo unit), Unit 100 (Changchun), Unit Ei 1644 (Nanjing), Unit 1855 (Beijing), Unit 8604 (Guangzhou), Unit 200 (Manchuria) and Unit 9420 (Singapore).
Many of the scientists involved in Unit 731 went on to prominent careers in post-war politics, academia, business, and medicine. Some were arrested by Soviet forces and tried at the Khabarovsk War Crime Trials; others, who surrendered to the Americans, were granted amnesty in exchange for access to the data collected by them.[7]
On 6 May 1947, Douglas MacArthur, as Supreme Commander of the Allied Forces, wrote to Washington that "additional data, possibly some statements from Ishii probably can be obtained by informing Japanese involved that information will be retained in intelligence channels and will not be employed as 'War Crimes' evidence."[8] The deal was concluded in 1948.
Because of their brutality, Unit 731's actions have now been declared by the United Nations to have been crimes against humanity.
In 1932, General Shiro Ishii (石井四郎), chief medical officer of the Japanese Army and protégé of Army Minister Sadao Araki was placed in command of the Army Epidemic Prevention Research Laboratory. He and his men built the Zhong Ma Prison Camp (whose main building was known locally as the Zhongma Fortress), a prison/experimentation camp in Beiyinhe, a village 100 kilometers south of Harbin on the South Manchurian Railway.
Ishii organized a secret research group, the "Togo Unit", for the conduct of various chemical and biological investigations. In 1935, a jailbreak, and later, an explosion (believed to be an attack) forced Ishii to shut down Zhongma Fortress. He later moved to Pingfang, approximately 24 kilometers south of Harbin, to set up a new and much larger facility.[9]
In 1936, Emperor Shōwa authorized, by imperial decree, the expansion of this unit and its integration into the Kwantung Army as the Epidemic Prevention Department.[10] It was divided at the same time into the "Ishii Unit" and "Wakamatsu Unit" with a base in Hsinking. From August 1940, all these units were known collectively as the "Epidemic Prevention and Water Purification Department of the Kwantung Army (関東軍防疫給水部本部)"[11] or "Unit 731" (満州第731部隊) for short.
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A special project code-named Maruta used human beings for experiments. Test subjects were gathered from the surrounding population and were sometimes referred to euphemistically as "logs" (丸太 maruta?).[12] This term originated as a joke on the part of the staff due to the fact that the official cover story for the facility given to the local authorities was that it was a lumber mill.[13]
The test subjects were selected to give a wide cross section of the population, and included common criminals, captured bandits and anti-Japanese partisans, political prisoners, and also people rounded up by the secret police for alleged "suspicious activities" and included infants, the elderly, and pregnant women.
In 2007, Doctor Ken Yuasa testified to the Japan Times that "I was afraid during my first vivisection, but the second time around, it was much easier. By the third time, I was willing to do it." He believes at least 1,000 persons, including surgeons, were involved in vivisections over mainland China.[19]
Prisoners were subjected to other experiments such as:
Japanese scientists performed tests on prisoners with plague, cholera, smallpox, botulism and other diseases.[22] This research led to the development of the defoliation bacilli bomb and the flea bomb used to spread the bubonic plague.[23] Some of these bombs were designed with ceramic (porcelain) shells, an idea proposed by Ishii in 1938.
These bombs enabled Japanese soldiers to launch biological attacks, infecting agriculture, reservoirs, wells, and other areas with anthrax, plague-carrier fleas, typhoid, dysentery, cholera, and other deadly pathogens. During biological bomb experiments, scientists dressed in protective suits would examine the dying victims. Infected food supplies and clothing were dropped by airplane into areas of China not occupied by Japanese forces. In addition, poisoned food and candies were given out to unsuspecting victims and children, and examined.
Unit 731 was divided into eight divisions:
The Unit 731 complex covered six square kilometers and consisted of more than 150 buildings. The design of the facilities made them hard to destroy by bombing. The complex contained various factories. It had around 4,500 containers to be used to raise fleas, six giant cauldrons to produce various chemicals and around 1,800 containers to produce biological agents. Approximately 30 kg of bubonic plague bacteria could be produced in several days.
Some of Unit 731's satellite facilities are in use by various Chinese industrial concerns. A portion has been preserved and is open to visitors as a War Crimes Museum.
Tons of biological weapons (and some chemicals) were stored in various places in northeastern China throughout the war. The Japanese attempted to destroy evidence of the facilities after disbanding. In August 2003, 29 people were hospitalized after a construction crew in Heilongjiang inadvertently dug up chemical shells that had been buried deep in the soil more than 50 years before.
This site was an open air testing area about 120 km from the Pingfang facility.
Headquarters of "Wakamatsu Unit" (Unit 100), under command of veterinarian Wakamatsu Yujiro. This facility dedicated itself to both the study of animal vaccines to protect Japanese resources, and, especially, veterinary biological-warfare. Diseases were tested for use against the Soviet and Chinese horses and other livestock. In addition to these tests, Unit 100 ran a bacteria factory to produce the pathogens needed by other units. Biological sabotage testing was also handled at this facility: everything from poisons to chemical crop destruction.
This HQ served as the headquarters of Unit 1855. It was also an experimental branch unit based at Tsinan, Shantung. Pandemic diseases were extensively studied at this facility.
This section was the headquarters of the "Tama Unit" (Unit Ei 1644) and conducted extensive joint projects and operations with Unit 731.
The headquarters of the "Nami Unit" (Unit 8604). This installation conducted human experimentation in food and water deprivation as well as water-borne typhus. In addition, this facility served as the main rat-farm for the medical units to provide them with bubonic plague vectors for experiments.
Formed in 1942, by Ryoichi Naito, Unit 9420 had approximately 1000 personnel based at the Raffles Medical University. The unit was commanded by Major General Kitagawa Masataka and supported by the Japanese Southern Army Headquarters.
There were two main sub units: the "Kono Unit," which specialized in malaria, and "Umeoka Unit," which dealt with the plague. In addition to disease experiments, this facility served as one of the main rat catching and processing centers. Evidence points towards this facility supplying a medical sub-unit operating in Thailand, with diseases for unknown operations and or experiments.
A top secret factory in Ōkunoshima produced chemical weapons for the Japanese military and medical units. Starting with mustard gas production in 1928, the factory moved on to such poisons as Yperite, Lewisite, and Cyanogen. During the 1930s, as the war in China grew worse, the island the factory sat on was removed from most maps to strengthen secrecy and security.
This unit was associated directly with Unit 731, and worked mainly in plague research.
This section, with unknown headquarters, was another unit that worked directly and extensively with Unit 731.
Special units led by Ishii Shiro's elder brother and only staffed with members from Ishii's home town operated separately from the regular medical organizations as roving researchers and trouble shooters.
Units with special and unknown assignments in Manchuria and the Asian mainland. It has been suggested that nuclear weapons research was conducted in Manchuria towards the end of the war by this branch.
Operations and experiments continued until the end of the war. Ishii had wanted to use biological weapons in the Pacific conflict since May 1944, but his attempts were repeatedly foiled by poor planning and Allied intervention.
With the Russian invasion of Manchukuo and Mengjiang in August 1945, the unit had to abandon their work in haste. The members and their families fled to Japan.
Ishii ordered every member of the group "to take the secret to the grave," threatening to find them if they failed, and prohibiting any of them from going into public work back in Japan. Potassium cyanide vials were issued for use in the event that the remaining personnel were captured.
Skeleton crews of Ishii's Japanese troops blew the compound up in the final days of the war to destroy evidence of their activities, but most were so well constructed that they survived somewhat intact as a testimony to what had happened there.
After Imperial Japan surrendered to the Allies in 1945, Douglas MacArthur became the Supreme Commander of the Allied Powers, rebuilding Japan during the Allied occupation. MacArthur secretly granted immunity to the physicians of Unit 731 in exchange for providing America with their research on biological warfare.
The United States believed that the research data was valuable because the allies had never publicly conducted or condoned such experiments on humans due to moral and political revulsion. The United States also did not want other nations, particularly the Soviet Union, to acquire data on biological weapons, not to mention the military benefits of such research.[24]
The Tokyo War Crimes Tribunal heard only one reference to Japanese experiments with "poisonous serums" on Chinese civilians. This took place in August 1946 and was actioned by David Sutton, assistant to the Chinese prosecutor. The Japanese defense counselor argued that the claim was vague and uncorroborated and it was dismissed by the tribunal president, Sir William Webb, for lack of evidence. The subject was not pursued further by Sutton, who was likely aware of Unit 731's activities. His reference to it at the trial is believed to have been accidental.
Although publicly silent on the issue at the Tokyo trials, the Soviet Union pursued the case and prosecuted twelve top military leaders and scientists from Unit 731 and its affiliated biological-war prisons Unit 1644 in Nanjing, and Unit 100 in Changchun, in the Khabarovsk War Crime Trials. Included among the prosecuted for war crimes including germ warfare was General Otozo Yamada, the commander-in-chief of the million man Kwantung Army occupying Manchuria.
Many Russian civilians, including women and children, and Soviet POWs held by Japan were killed in chemical and biological warfare experiments by Unit 731, along with the Chinese people, American POWs, Russian and other nationalities.[25] The trial of those captured Japanese perpetrators was held in Khabarovsk in December 1949.
A lengthy partial transcript of the trial proceedings was published in different languages the following year by a Moscow foreign languages press, including an English language edition: Materials on the Trial of Former Servicemen of the Japanese Army Charged with Manufacturing and Employing Bacteriological Weapons (Moscow: Foreign Languages Publishing House, 1950).
This book remains an invaluable resource for historians on the organization and activities of the Japanese biological warfare "death factory" lab-prisons. The lead prosecuting attorney at the Khabarovsk trial was Lev Smirnov, who had been one of the top Soviet prosecutors at the Nuremberg Trials.
After World War II, the Soviet Union built a biological weapons facility in Sverdlovsk using documentation captured from Unit 731 in Manchuria.[26]
The Japanese doctors and army commanders who had perpetrated the Unit 731 atrocities and germ warfare experiments received sentences ranging from 2 to 25 years in a Siberian labor camp from the Khabarovsk court.
Some former members of Unit 731 became part of the Japanese medical establishment. Dr Masaji Kitano led Japan's largest pharmaceutical company, the Green Cross. Others headed U.S.-backed medical schools or worked for the Japanese health ministry. Shiro Ishii in particular moved to Maryland to work on bio-weapons research.[27]
Imperial Japanese Army special research units |
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Unit 100 (Shenyang) | Unit 516 (Qiqihar) | Unit 543 (Hailar) | Unit 731 (Pingfang) / Unit 200 (Manchuria) / Unit 8604 or Nami Unit (Guangzhou) | Unit 773 (Songo) | Unit Ei 1644 (Nanjing) | Unit 1855 (Nanjing) | Unit 2646 or Unit 80 (Hailar) | Unit 9420 or Oka Unit (Singapore) |
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