731 Squadron

The Unit 731 was a covert program of research and development of biological weapons the Imperial Japanese Army , which carried out deadly medical experiments on humans during the Second Sino-Japanese War (1937-1945) and World War II . He was responsible for some of the most horrible war crimes committed in modern times. Officially known by the Imperial Japanese Army as the Research and Epidemic Prevention Laboratory of the Kempeitai Political Ministry , it was initially established as a political and ideological section of the Kempeitai military police . It was formed with the intention of counteracting the political-ideological influence of the enemy and reinforcing the system of military unity .

The squad was camouflaged as a water purification module located in the Pingfang district, northeast of the Chinese city of Harbin , part of the puppet government of Manchukuo . It operated through Japanese political propaganda and as an ideological emblem of the political branch of the army called Kōdōha ( War Party ). In the first phase, this section acted against communist propaganda, but extended its responsibilities in other directions, both in Japan and abroad.

It became an approximate equivalent of the Nazi Schutzstaffel . It promoted belief in Japanese racial supremacy , racist theories , counter- espionage, investigation , political sabotage and infiltration into enemy lines. It has also been linked with the Manchukuo military police, the Manchu intelligence service, the ordinary Manchu police, Manchu Committees, regional Manchu nationalist parties and the Japanese Secret Service detachment in Manchukuo .

Up to ten thousand people, both civilian and military, of origin Chinese , Korean , Mongolian and Russian were the subject of experimentation led by Squadron 731. 1 Some POWs Americans and Europeans also were killed Squadron 731. 2 Other than that , The use of biological weapons developed by the 731 Squadron’s biochemical weapons program resulted in tens of thousands of deaths in China – possibly as many as 200,000 casualties by some calculations. 3

The 731 Squadron was one of the many detachments used by the Japanese Armed Forces for research on biological agents for warfare; other tactics and administrative units were the Squadron 516 ( Qiqihar ), the Squadron 543 ( Hailar ), the Squadron 773 (Songo), the Unit 100 ( Changchun ), the Squadron 1644 ( Nanking ), the Squadron 1855 ( Beijing ), the Squadron 8604 ( Canton ), the Squadron 200 ( Manchuria ) and the Squadron 9420 ( Singapore ).

Many of the scientists involved in the 731 Squadron continued their prominent careers in politics , education , business and medicine . Some were arrested by Soviet forces and prosecuted in Khabarovsk war crimes trials ; Others who surrendered to the Americans, were granted amnesty in exchange for access to the information collected by them. 4

Because of its brutality, the actions of the 731 Squadron have been denounced today by the United Nations as war crimes.


Shirō Ishii , Commander of the 731 Squadron

In 1932, Chūjō (Lieutenant General ) Shirō Ishii was placed in command of the Army Research Laboratory on Epidemic Prevention . He and his men built the Zhong Ma Prison Camp (whose main building was known locally as Zhongma Fortress ), an experimental prison located in Bei-inho village, 100 kilometers south of Harbin . The Manchu railways were placed to transport materials and equipment. Ishii organized the secret research group “Tōgō Unit”, for the coordination of chemical and biological studies. A prisoner’s escape in 1934 and an explosion in 1935 (alleged attack), forced Ishii to suspend the operations of Zhongma Fortress. Ishii later moved to Pingfang, about 15 miles south of Harbin, to install a new, larger complex. 5

Later this unit was incorporated into the Kwantung Army as the Epidemic Prevention Department, but was simultaneously divided into the “Ishii Unit” and the “Wakamatsu Unit”, with a central command in Hsinking . From 1941, all these units were known collectively as the Department of Epidemic Prevention and Water Purification of the Army of Kwantung or Squadron 731 as nickname. They had the backing of the Imperial Youth Corps , the Japanese Research University and the Kempeitai . Some sources relate them to the zaibatsu Mitsui , monopoly of the poppy cultivation in Manchukuo (for the production of heroin ).

Members of the 731 Squadron

  • Chūjō (Lieutenant General ) Shirō Ishii
  • Chūsa (Lieutenant Colonel ) Ryoichi Naito
  • Dr. Masaji Kitano
  • Yoshio Shinozuka
  • Yasuji Kaneko


The 731 Squadron was composed of 8 Divisions:

  • Division 1: conducted research on bubonic plague , cholera , anthrax and tuberculosis , using humans. To this end, a prison was built with capacity for 300 or 400 prisoners.
  • Division 2: was tasked with biological weapons, focusing on the design and manufacture of devices to spread pathogens and parasites.
  • Division 3: was engaged in producing projectiles loaded with pathogens. She was quartered in Harbin.
  • Division 4: produced various materials for the experiments.
  • Division 5: trained new staff members.
  • Divisions 6, 7 and 8: units of medical, medical and administrative supplies, respectively.


During the second Sino-Japanese war, a special medical project with the key name of ‘Maruta’ used humans to experiment. The test subjects (military and civil) were gathered from the surrounding population and in some cases euphemistically referred to as “logs” (maruta, 太 太). 6 This term, originated from a “joke” on the part of the personnel due to the fact that the official information on the establishment offered to the local authorities, was that it was a sawmill. Among the test subjects were children, elderly and pregnant women. Many experiments and vivisections were performed without the use of anesthetics on the arms and legs of the victims because they were believed to influence the results or were unnecessary because the individuals were tied. 6


  • Prisoners of war were subjected to vivisection (dissection when still alive) without anesthesia . 7 6
  • The vivisections were performed on prisoners infected with various diseases. The scientists carried out invasive surgery on captives, removing organs to study the effects of the disease on the human body. These were performed while the patients were alive, because it was believed that the decomposition process would affect the results. 8 6 Among the infected and vivisected prisoners were men, women, children and infants. Referring to Fig.
  • The vivisections were also perpetrated in pregnant women, sometimes pregnant by the same doctors, and the fetuses were extracted. 10
  • The limbs of the prisoners were amputated in order to study the loss of blood.
  • These removed limbs were sometimes rejoined from the opposite side of the body.
  • At other times prisoners’ limbs were frozen and amputated, while other limbs were frozen and then thawed to analyze the effects of the resulting gangrene and putrefaction without treatment.
  • Some prisoners were surgically extracted the stomach and were linked the esophagus to the intestines .
  • Parts of the brain , lungs , liver , etc., were extirpated from some prisoners. 11 7 6

Test of weapons

  • Human targets were used to test grenades placed at various distances and in different positions. 6
  • Flamethrowers were tested on humans. 6
  • People were tied to posts and used as targets to test germ pumps, chemical weapons and conventional bombs . 6

Experiments with pathogens

  • Prisoners were injected with sera contaminated with pathogens, looking like vaccines , to study their effects. 6
  • To investigate the impact of sexually transmitted diseases untreated, male and female prisoners were deliberately infected with syphilis and gonorrhea , then were studied.
  • Prisoners were infested with fleas transmitting the bubonic plague to analyze the viability of a biological warfare.

Biological attacks

  • Parasites, infected clothing and contaminated supplies were thrown into bombs on various targets. The resulting epidemics of cholera , anthrax and bubonic plague were responsible for killing about 400,000 Chinese. 6
  • The 731 Squadron and its affiliated units (Squadron 1644, Squadron 100 etc.), surpassed the “test” phase of biological weapons and carried out biological attacks against the Chinese people (both civilians and soldiers) during the course of the Second World War. Fleas infected with pestilence were bred in laboratory facilities of the 731 Squadron and 1644 Squadron, being scattered by airplanes over inhabited Chinese locales, such as the coastal city of Ningbo in 1940 and the city of Changde in 1941. This aerial-military spray Resulted in human epidemics of bubonic plague that killed thousands of Chinese civilians . 12
  • Tularemia experienced with Chinese civilians. 13

Other experiments

  • Some prisoners were hung upside down to observe how long it would take them to asphyxiate. 6
  • Others were injected air into the arteries to determine the time it took them to show the initial symptoms of an embolus . 6
  • Some captives were injected with horse urine into their kidneys. 6
  • Others were deprived of food, water and sleep to specify the length of time to death.
  • Other prisoners were placed inside vacuum chambers until they died.
  • Others were exposed to extreme temperatures developing freezing , being analyzed how long the human body survived with such torment, in addition to determining the effects of putrefaction and gangrene on human flesh. 6
  • Some experiments were performed to define the relationship between temperature, burns and human survival.
  • A few prisoners were put into centrifuges , turning them to death.
  • Animal blood was injected into a few others, studying the effects of this action.
  • Some captives were irradiated with lethal doses of x – rays .
  • In gas chambers were tested several chemical weapons, always using people.
  • Air bubbles were injected into the bloodstream of other prisoners to simulate a stroke . 6
  • Sea water was also injected into as many captives to determine whether it could serve as a substitute for saline .
  • Mothers with babies put them in a tank that filled with water and watched the behavior of the mother (who at first held the baby to the top but then ended up stepping on it so she did not drown herself).


Japanese scientists conducted tests on prisoners focusing on bubonic plague , cholera , smallpox , botulism and other diseases. 14

These experiments led to the development of the defoliating bacillus bomb and the flea bomb used to spread bubonic plague . 15 Some of these bombs were designed with ceramic bodies ( porcelain ), an idea proposed by Ishii in 1938.

These bombs enabled Japanese soldiers to launch biological attacks, contaminating crops, reservoirs, springs and other areas with anthrax , fleas infected with plague, typhoid , dysentery , cholera and other deadly pathogens.

In addition to this, contaminated food supplies and even clothing were dropped from aircraft within areas of China not occupied by Japanese military forces.


One of the buildings open to tourists.

The base of the 731 Squadron occupied six square kilometers and consisted of more than 150 buildings. The facilities were very well designed, being difficult to destroy. Some satellite buildings of the 731 Squadron still exist and are open to the public , while in others operate factories of various Chinese companies.

The complex contains several factories. There were about 4500 containers that were used to raise fleas , six giant boilers to produce various chemical substances and about 1800 containers to produce biological agents. Approximately 30 kilograms of bubonic plague bacillus could be produced in several days.

Tons of these biological weapons (and some chemicals) were stored in various parts of northeastern China during the course of the war.

The Japanese attempt to destroy the evidence of settlement after being disrupted by the squad failed because the remains occasionally damaged civilians, even recently.

In August 2003 , 29 people were hospitalized after a group of builders Heilongjiang unearth some chemical shells that had been buried deep in the ground more than fifty years ago.

Anta test site

This was an outdoor test area located 120 kilometers from the Pingfang facility .

Hsinking Operations Center (Changchung)

The central command of the “Wakamatsu Unit” ( Squadron 100 ) was under the command of veterinarian Yujiro Wakamatsu . This facility was dedicated to the study of vaccines to protect Japanese animal resources and, especially, veterinary biological warfare. The diseases were tested for use against Soviet and Chinese horses and other types of cattle. In addition to these tests, Squadron 100 directed a bacterial factory to produce the pathogens required by other units. Biological sabotage tests were also conducted at this facility: from poisons to chemical destruction of crops.

Peiping Operations Center

This was the command of the Squadron 1855 . It was also an experimental branch located in Chinan , Hebei . The bubonic plague and other diseases were studied extensively in these facilities.

Nanking Operations Center

This was the command of the “Tama Unit” ( Squadron 1644 ). This section conducted common projects and operations with the 731 Squadron.

Operations Center Guangdong (Canton)

The headquarters of the “Nami Unit” ( Squadron 8604 ). This facility spearheaded experimentation on deprivation of food and water to humans, as well as waterborne transmission of typhus . In addition, this facility served as the main farm rats to supply medical units with the vectors of bubonic plague for experiments.

Syonan Operations Center (Singapore)

Formed in 1942 , by Naito Ryoichi , Squadron 9420 had approximately 1000 workers based at Raffles Medical University . The squadron was commanded by Major General Kitagawa Masataka and supported by the southern commandos of the Japanese Imperial Army.

There were two main subunits: the “Umeoka Unit”, specialized in malaria , and the “Kono Unit”, which dealt with the bubonic plague . In addition to the experiments with diseases, this facility served as one of the main centers of capture and dissection of rats.

Hiroshima Operations Center

A highly confidential factory on the island Okunoshima produced chemical weapons for the Japanese military and medical units. Beginning with the production of mustard gas in 1928 , the factory continued to be linked to the development of chemical weapons such as phosgene , lewisite , and cyanogen . During the 1930s, as the war worsened in China, the island where the factory was found was erased from most maps to strengthen confidentiality and security.

Operations Center Manchuria (Squadron 200)

This unit was directly associated with the 731 Squadron and worked mainly in the plague investigation.

Operations Center Manchuria (Squadron 571)

This section, with unknown headquarters, was another unit that worked directly and extensively with the 731 Squadron.

Special ambulance brigades

They were special units led by Shiro Ishii’s older brother and only staffed by Ishii’s hometown. They operated separately from regular medical organizations as researchers and problem solvers.

Special Operations Units

Units with special and unknown assignments in Manchuria and the Asian continent. It has been hinted that nuclear research was conducted in Manchuria towards the end of the war by this division.

Dissolution at the end of World War II

Poster of information located in the place today.

Operations and experiments continued until the end of the war. Shirō Ishii wished to use biological weapons in the Pacific conflict since May 1944, but his attempts failed repeatedly on the poor formulation of plans and Allied intervention. With the Russian invasion of Manchukuo and Mengjiang in August 1945, the unit had to relinquish its work. The members and their families fled through Manchuria and China to return to Japan.

Ishii ordered each member of the group to “carry the secret to the grave”, threatening to find them if they failed and preventing anyone working in public positions in Japan. Ampoules were distributed with potassium cyanide , to be used in case the remaining personnel were captured.

Confidence officers of Ishii’s Japanese troops dynamited the facilities in the final days of the war to destroy the evidence of their activities, but most were so well built that they survived somewhat unscathed, standing as testimony to what happened there.

After Japan surrendered to the Allies in 1945, Douglas MacArthur became Supreme Commander of the Allied Forces , rebuilding Japan during the Allied occupation .

At the end of the war, he secretly granted immunity to the physicians of the 731 Squadron in exchange for providing the United States with his biological warfare research data . The United States believed that the research data was valuable because the Allies never publicly prosecuted or condemned such experiments in humans because of moral and political aversion. The United States also did not want other nations, such as the Soviet Union , to acquire data on biological weapons , not to mention the military advantages of such research. 16

The Tokyo War Crimes Tribunal had only learned through a reference to Japanese experiments with “infected sera” in Chinese civilians. This happened in August of 1946 and was denounced by David Sutton, assistant of the Chinese prosecutor.

Japanese defense counsel Michael Levin argued that the allegation was vague and uncorroborated, being overturned by court chief William Webb for lack of evidence. The subject was not further investigated by Sutton, who was probably aware of the activities of the 731 Squadron. It is believed that his reference to this in the trial may have been accidental.

Although publicly silenced, in the Tokyo Trial incident the Soviet Union followed the case and prosecuted twelve leaders and scientists of the 731 Squadron and its filial units: the 1644 Squadron in Nanking and the 100 Squadron in Changchun, all in the Trials of Khabarovsk . Among those war criminals were General Otozō Yamada, the commander-in-chief of a million Japanese soldiers occupying Manchuria.

Many Soviet prisoners of war captured by Japan and Russian civilians, including women and children, were killed in chemical and biological experiments of the 731 Squadron, along with Chinese, Koreans, Mongols and captives of other nationalities. The trial of the Japanese authors who were captured was carried out in the city of Khabarovsk in the Russian Far East near the border with northeastern China in December 1949. A very long partial transcript of the trial proceedings was Published in several languages ​​the following year by a Moscow journalism agency in foreign languages, including an English 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 about the organization and activities of biological warfare attempts. Interestingly, none of the foreign language editions of this book had any information about their number of printing – only the Russian edition says that about 50,000 copies were published. Lev Smirnov, who had been one of the Soviet prosecutors in the Nuremberg trials against the Nazi doctors who had committed human atrocities in similar experiments in the death camps like Auschwitz and Dachau, was the lawyer in the Khabarovsk trials .

The galenos and officers of the Imperial Japanese Army who had perpetrated the atrocities of the 731 Squadron received sentences of 2 to 25 years of confinement in labor camps, by the court of Khabarovsk. All the doctors got the amnesty.

The 731 Squadron in the cinema

The men behind the sun (Tun Fei Mou, 1988) shows the atrocities committed by the 731 Squadron. The film is made in honor of the victims with the intention of not forgetting what happened. Its original title is “Hei tai yang 731”. This film had a sequel inspired by the same facts, The Laboratory of the Devil , (Godfrey Ho, 1992). Its original title is “Hei Tai Yang 731 Xu Ji Zhi Sha Ren Gong Chang”.

The film philosophy of a knife (in English: Philosophy of a knife ), directed by Andrey Iskanov and released in June 2008, also talks about the atrocities Squadron Unit 731 or 731. Similarly , the film is dedicated to the victims, With the intention of not repeating itself, even in the name of science, as it was said at the time.

The 731 Squadron in music

Unit 731 is a song inspired by the actions of the 731 Squadron, written by Jeff Hanneman of the American band of thrash metal Slayer . “Kagome kagome” is an original vocaloid song that deals with the mutilations that the children underwent of such cruel experiment to find the pill of the eternal life, among other studies.

The 731 Squadron on television

Episode 10 of Season 3 of the X-Files series is titled 731 and is about a group of doctors experimenting with humans with the intention of creating a hybrid human and extraterrestrial. Curiously, this was the most watched episode in Spain of that series. [ Citation needed ]

See also

War of the Pacific (World War II)

  • Japanese war crimes
  • Manila Massacre
  • Nanquin Massacre
  • Second Sino-Japanese War
  • Sook Ching Massacre

Germany Nazi

  • Nazi Medical Experimentation
  • Josef Mengele
  • Herta Oberheuser


  1. Back to top↑ http://www.chinadaily.com.cn/en/doc/2003-10/17/content_273165.htm – Book published on the crimes of the Japanese biological warfare.
  2. Back to top↑ http://english.people.com.cn/200508/03/eng20050803_200004.html – Abandoned secret files of the 731 Squadron.
  3. Back to top↑ http://www.globalsecurity.org/wmd/world/japan/bw.htm – Biological Weapons Program.
  4. Back to top↑ http://www.fas.org/nuke/guide/usa/cbw/bw.htm – Biological weapons.
  5. Back to top↑ Harris, Sheldon H. Factories of Death: Japanese Biological Warfare 1932-45 and the American Cover-Up , Routledge, 1994. ISBN 0-415-09105-5 ISBN 0-415-93214-9 . Page 26> Establishment of Zhong Ma Prison, page 33> Creation of Pingfang Counterpart.
  6. ↑ Jump to:a b c d e f g h i j k l m n ñ Christopher Hudson (March 2, 2007). Doctors of Depravity . Daily Mail.
  7. ↑ Jump to:a b Richard Lloyd Parry (February 25, 2007). Dissect them alive: order not to be disobeyed . Times Online.
  8. Back to top↑ Interview with the former member of the squadron 731; Nobuo Kamada
  9. Back to top↑ “Unmasked Horror” Nicholas D. Kristof (March 17, 1995) New York Times. A special report .; Japan Confronting Gruesome War Atrocity
  10. Back to top↑ Uncovering a deadly secret vivisection photographs
  11. Back to top↑ Japan admits dissecting prisoners of war in World War II James Bauer. “Japanese Unit 731 Biological Warfare Unit” Viewed January 16, 2007
  12. Back to top↑ Barenblatt, Daniel. A Plague Upon Humanity: The Secret Genocide of Axis Japan’s Germ Warfare Operation , HarperCollins, 2004. ISBN 0-06-018625-9
  13. Back to top↑ Source: CDC.gov
  14. Back to top↑ Japanese Biological Weapons Program Federation of American Scientists
  15. Back to top↑ Review of Biological Warfare Studies Tien-wei Wu A Preliminary Review of Studies of Japanese Biological Warfare and Unit 731 in the United States
  16. Back to top↑ http://news.bbc.co.uk/2/hi/programmes/correspondent/1796044.stm – Squadron 731: Biological Force of Japan.