What happened to the doctors of Unit 731 after the Japanese surrender? IBDP History Internal Assessment

What happened to the doctors of Unit 731 after the Japanese surrender? IBDP History Internal Assessment

International Baccalaureate History Internal Assessment

What happened to the doctors of Unit 731 after the Japanese surrender?

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Section 1: Identification and Evaluation of Sources

This investigation examines the question: What happened to the doctors of Unit 731 after the Japanese surrender? Unit 731 was a base for Japanese research on biological warfare (BW). Under the order of Japan's Emperor Hirohito, the programme was established by Dr Shiro Ishii in 1932 in Japan. After Japan occupied Manchuria, the program rose to its final stage, having the opportunity to execute experiments on war prisoners in occupied China.

Source A: A report to the Chief of Chemical Corps of the United States in Camp Detrick, “A brief summary of new information about Japanese biological warfare activities”, dated on the 20th of June 1947 and written by the Chief of PP-E (Pharmacology, Physiology, Evaluation).1

Dated 1947, it outlines the US military's internal view of the BW program conducted in Unit 731. As a Top-Secret intelligence document, its origin provides strong immediacy and relevance as a firsthand account written by high-ranking officials of the United States military. Its purpose was to provide a briefing on the results of interviews conducted with doctors and investigations on Unit 731. Consequently, it gives an unfiltered assessment of Unit 731 from the US military standpoint.

The content of the source summarises the findings on the experiments conducted by magnitude and classification, giving direct numbers, e.g. “more than 200 human cases of disease caused by BW agents”. Also, further insights were promised in the document, from the director of Unit 731, Dr Shiro Ishii, in the form of a “treatise”.

However, the source is limited as it primarily reflects the US military viewpoint and strategic interests, thereby excluding crucial perspectives of the Japanese military, the Chinese civil society, as well as the victims of the Unit 731 experiments. The selective US narrative produces a strategically framed bias, rooted in its origin as an intelligence document.

Additionally, this contemporary source omits ethical evaluations and long-term legal consequences for the doctors involved with Unit 731. This limits the source’s contribution to evaluating justice after the war.

Source B: The book “Hidden Atrocities: Japanese Germ Warfare and American Obstruction of Justice at the Tokyo Trial” by Jeanne Guillemin, published in 2017.2

This secondary source focuses on American-East Asian relations, providing a detailed historical analysis of the relations between the US military and Unit 731 doctors. It was written by a historian in 2017, which offers the author broad access to archives and evaluating multiple trials for a more comprehensive historical interpretation.

The purpose of the source was to argue that obstruction of justice occurred in the actions taken by the United States (U.S.) after the Japanese surrender. Therefore, it interprets the American objectives, arguing the U.S. motive in the Khabarovsk Trial. The book contains factual data and names doctors and authority figures involved. It draws on the documented trial, which enhances reliability in the functional foundation of the source.

The source is valuable to this investigation since it examines how the United States dealt with the doctors of Unit 731, allowing insight into how justice was avoided, therefore directly addressing the question of this investigation.

This source could reflect hindsight bias, as it was written in 2017, long after the events occurred. Therefore, later access to information, as well as new established narratives, could shift the author's interpretation of the actions taken by the U.S. military. In addition, the secondary source could have been influenced by the personal opinion of the author or shaped to align with the intended purpose to reconsider.

Section 2: Investigation

After the Japanese surrender, Ishii issued an order to blow up the site of Unit 731 to not leave behind any significant material.3 Some involved got captured by the Soviets as they advanced into Manchuria. The captured were held in the Soviet hands as war prisoners and sentenced to trial in Khabarovsk.4 This section examines the intention behind the trial and what happened to the war prisoners that were captured and the doctors/workers that weren't.

After Japan's defeat, the United States favoured advancing its military interests in return for not seeking justice. The priority was the BW data of Unit 731.5 The reasoning according to MacArthur was that: “The value to the United States of Japanese BW data is of such importance to national security as to far outweigh the value accruing from ‘war crimes’ prosecution.”6

Although Ishii warned everyone not to let any information out, as interviews were made by the team of Fort Detrick, the BW institution of the United States, the doctors were cooperative, in the hopes of a mild treatment from the U.S. military.7 Following, Ishii staged his own death and quietly returned home, his behaviour indicating consciousness of guilt and fear of liability. Discovery of Ishii's staged death resulted in an interview at his house in Tokyo.8 Ishii offered information if he was granted immunity.9 Ishii said, “I would like to be hired by the United States as a biological warfare expert. In preparation for the war with Russia, I can give you the advantage of my 20 years of research and experience.”10 This immunity deal, accepted by the United States military, was extended beyond Ishii to others who had been tied to working at Unit 731.11 If people became aware of Unit 731, the U.S. military had a plan to point out “lack of solid evidence that experiments and BW had in fact occurred”.12 This marked the beginning of the collaboration of Japanese doctors of Unit 731 and the United States military, yet it came with the expense of justice for the countless victims of Unit 731.13 The Unit 731 doctors aimed to escape prosecution, while the U.S. military made an effort to gain BW data.

General MacArthur and the United States military made a significant effort to conceal the truth about the immunity deals.14 Therefore, it was deeply concerning that the USSR had captured personnel linked to Unit 731.15 Much of the evidence given in the trial was dismissed as negligible, as Stalin was infamous for his show trials in the Western world. All twelve defendents were involved with BW activities, but only six were involved in the “731 detachment”. All twelve pleaded guilty and were sentenced to 2-25 years in prison or hard labour.16 General MacArthur, in response to the verdict, made a statement from his office in Tokyo. He tried to “denounce the Khabarovsk trial and Izvestia's charges of Japanese BW and a United States cover-up as false communist propaganda”.17 Although the Khabarovsk trial was first dismissed as propaganda, it nonetheless created a political threat that was detrimental to the United States' effort to conceal immunity agreements with the doctors of Unit 731.

The doctors initially denied having ever used Soviet war prisoners in their experiments, as recorded in Source A.18 Nevertheless, the motive for capturing the doctors and putting them on trial was Unit 731's proximity to Soviet borders, propaganda and revenge for the atrocities some Soviet war prisoners went through in Unit 731.19 The infamous trial was held in Khabarovsk, a remote location, and announced on short notice, thereby excluding foreign reporters, enhancing the success of the propaganda campaign.20 Therefore, the Soviets had the opportunity to reinforce their perspective internationally. Moreover, the evidence presented was translated by a Soviet "Senior Interpreter, Master of Historical Sciences" named Podpaldova and the trial primarily presented evidence to support a Soviet-driven narrative.21 As a result, the evidence's credibility is questionable, as it was accessible for manipulation. Although the American ambassador in Moscow believed that the trial was likely one of Stalin's long-planned “show trials",22 the USSR had been pressuring the United States authorities to hand over a former Unit 731 worker for trial unsuccessfully.23 Nonetheless, the members of the BW activity in the Trial were considered to represent a wide range of roles and responsibilities.24 For instance, Yamada Otozoo, the Commander-in-Chief of the Japanese Kwantung Army, was part of the trial, as well as Kurushima Yuji, who served in Unit 731 as a laboratory assistant.25 It turned out that some of this evidence was considered to carry real value, which suggests that, despite the propagandistic intent, the Soviets attempted to reveal Japanese BW.26 The United States Army Intelligence reported that before the trial, the Soviets had been working with about thirty captured members of Unit 731.27 This is significant, as it demonstrates performative and selective accountability, characteristics of a show trial. The defendant's level of compliance indicates a high level of pressure from the Soviets, since the guilty pleas would undermine the United States efforts to cover up the immunity deals, effectively reducing the credibility of the trial.28

Reportedly, captured doctors were interrogated, suggesting a systematic interest in the Japanese BW program by the Soviets.29 The soviet BW scientist, Igor V. Domaradskij, stated in Soviet internal project reports that the doctors' experience of Unit 731 and the “large-scale cultures of bacteria and fleas” could be “useful” for the Soviet BW program.30 This suggests that the Soviets were not solely driven by revenge. That approach was, however, not exclusive to the Soviets. The doctors of Unit 731 had interviews with the United States as well as with the Soviet Union. When the tactical importance was recognised by the United States, the doctors were ordered “not to mention … the U.S. interviews” to the Soviets. Moreover, in the circumstance that the information was valuable, they would be instructed that “its divulgence to the Soviets should not be permitted”.31 This indicates that both countries saw the doctors as a strategic asset, competition over the data contributed to the rapid rise in tension between the USSR and the United States, foreshadowing the Cold War.

Many doctors went back to their lives undisturbed and unpunished.32 Those involved in the Khabarovsk trial (December 1949) went back to China after the release of all war prisoners in 1956, as China and the USSR were at peace.33 Ishii had secretly visited the United States BW station Fort Detrick to lecture on how to effectively conduct germ warfare.34 However, the United States was hesitant to allow some high-ranking officials from Unit 731 a return to careers in universities.35 Ishii, like many others, lived an anonymous, peaceful and comfortable life. In rare cases, he faced blackmail attempts, which were resolved through United States intelligence surveillance.36 This illustrates how the United States military actively protected the doctors and high-ranking officials, upholding their immunity agreement. Due to the high payment the doctors received while working at Unit 731, many went back to jobs similar to the area before, e.g. working for the Ministry of Health or Welfare. Meguro Masahiko, a pharmacist associated with Unit 731, states that “those are the people who built the foundation of today's Japan”.37 A few members of Unit 731 earned a reasonable amount of money as executives of pharmaceutical companies.38 Others continued working in education, for instance, the leader of the Anthrax division of Unit 731, became the Chief textbook investigator of the Ministry of Education.39 The involvement of former Unit 731 officials restricted the presentation of Unit 731-related events. This contributed to the limited acknowledgement of Unit 731 atrocities, within Japanese textbooks.40 Moreover, the emperor remained unprosecuted, as Britain and the United States opposed a trial for securing a stable surrender of Japan.41 As a result, measures taken to advance the United States immunity deal carried long-term consequences for Japanese postwar justice.

In conclusion, this investigation aimed to discover what happened to the doctors of Unit 731 after the Japanese surrender. The evidence shows that the doctors were granted immunity by the United States in return for data. Political and national interests played a greater role than the pursuit of justice and ethical accountability. In both cases, for the USSR and the United States, the data of Unit 731 became a Cold War resource.

Section C: Reflection

This investigation has helped me understand how historians reconstruct events based on the sources that have been shaped with secrecy, political influence and propaganda. Examining what happened to the Doctors and workers of Unit 731 after Japan's surrender has helped me gain knowledge on how to manage tampered sources, like the transcript of the Khabarovsk trial. I realised that politics determines what narrative of the story survives, one example is the Japanese textbook censorship.

My methodology included primary sources such as post-war United States Military records and the official Soviet transcript of the Khabarovsk trial. Additionally, secondary sources that have already been analysed by historians, such as the book “A Plague upon Humanity".

A limitation I faced was translation, as there were a few records and primary sources that were not accessible for me to analyse, and translations could have been tampered with. Furthermore, I struggled to balance out empathy for the victims and authentic evidence, which risked my analysis being too opinionated.

I noted that I had never heard of Unit 731 until I started this investigation, despite the severity and scale of the operation. Yet all over the world, we learn about the Holocaust, despite both disregarded human rights. This led me to reflect on how political interests like the immunity deal between the United States and doctors influence our current educational system.

Works Cited

Barenblatt, Daniel. 2004. A Plague upon Humanity: The Secret Genocide of Axis Japan's Germ Warfare Operation. New York: HarperCollins.

Chang, Iris. 1997. The Rape of Nanking: The Forgotten Holocaust of World War II. New York: BasicBooks.

Cunliffe, William H. 2006. Select Documents on Japanese War Crimes and Japanese Biological Warfare, 1934-2006. Washington, DC: National Archives. https://www.archives.gov/files/iwg/japanese-war-crimes/select-documents.pdf

Domaradskiĭ, Igorʹ V., and Wendy Orent. 2003. Biowarrior: inside the Soviet/Russian biological War machine. Amherst, NY: Prometheus Books.

Drea, Edward J. 2006. Researching Japanese War Crimes Records: Introductory Essays. Washington, DC: Nazi War Crimes and Japanese Imperial Government Records Interagency Working Group.

Gold, Hal. 1997. Unit 731: Testimonies. 1st ed. Tokyo: Tuttle Publishing.

Guillemin, Jeanne. 2017. Hidden Atrocities: Japanese Germ Warfare and American Obstruction of Justice at the Tokyo Trial. New York: Columbia University Press.

Harris, Sheldon H. 2002. Factories of Death: Japanese Biological Warfare, 1932-45, and the American Cover-up. London: Routledge.

Polunina, Valentyna. 2015. “Chapter 5, The Khabarovsk trial.” In Trials for International Crimes in Asia, 121-144. Cambridge: Cambridge University Press.

Rimmington, Anthony. 2021. The Soviet Union’s Invisible Weapons of Mass Destruction: Biopreparat's Covert Biological Warfare Programme. Cham: Springer.

“Russia Claims U. S. Prepares to use Diseases as War Weapons.” December 29, 1949. Radford News Article 4 (275): 6. https://www.jstor.org/stable/pdf/community.35146871.pdf.

Union of Soviet Socialist Republics. 1950. Materials on the trial of former servicemen of the Japanese army charged with manufacturing and employing bacteriological weapons. Moscow: Foreign Languages Publishing House.

Williams, Peter, and David Wallace. 1989. Unit 731: Japan's secret biological warfare in World War II. New York: Free Press.

Yang, Yan-Jun, and Ruqian Tan. 2018. Unit 731: Laboratory of the Devil, Auschwitz of the East: Japanese Biological Warfare in China 1933-45. Barnsley: Fonthill Media.

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Written by David Heath — Head of Humanities at the Bavarian International School, Dachau-accredited guide, Yad Vashem-certified educator and creator of Traces of Evil.
About David Heath
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