Japanese Archives Release Full Roster of Secret WWII Biological‑Warfare Unit 1644, Connecting It to the Infamous Unit 731

The significance of the revelation is difficult to overstate. Until now, the existence of Unit 1644 was known mainly through fragmentary testimonies, secondary research and occasional references in post‑war trials. The newly published roster confirms not only the unit’s official designation but also the names, ranks and service records of hundreds of officers, doctors, technicians and logisticians who were part of a programme that deliberately cultivated plague, anthrax, cholera, typhus and other lethal pathogens for use against Chinese civilians and soldiers. The documents also detail the unit’s logistical chain – the transport of infected insects, the construction of makeshift laboratories in occupied cities, and the coordination with the central hub of Japan’s biological weapons enterprise, Unit 731, which operated out of the infamous “Eagle” facility in Pingfang, Manchuria.

The historical context runs deep. In 1933, the Imperial Japanese Army established its first germ‑warfare detachments in the occupied territories of Northeast China, capturing civilians to serve as test subjects and launching covert attacks that would later be estimated to have caused tens of thousands of deaths. By April 18 1939, the army had formalised the “Rong‑character 1644” unit under the guise of the “Central China Epidemic Prevention and Water Supply Department,” also known as the “Tama Unit.” Its official front was a public health office, but its true purpose was the research, production and field deployment of bacterial agents. Unit 1644, like its sister formations in North, Central and South China, shared personnel, equipment and scientific expertise with Unit 731, and the two worked in tandem to test weapons on both prisoners of war and civilian populations.

The war’s end did not bring closure. When the Soviet Red Army swept into Manchuria in August 1945, most of the identifiable records of the biological programme were destroyed or hidden. The surviving archives were scattered among Japanese military headquarters, Soviet intelligence files and, later, the archives of the United States, which had offered the United States a degree of tacit protection to the Japanese scientists in exchange for data useful in the early Cold War arms race. In February 1950, the Soviet Union, after concluding its own war‑crimes trials, sent a diplomatic note to China, the United States, the United Kingdom and France summarising its findings on Japan’s germ‑warfare crimes and urging an international military tribunal. The note, however, remained largely ignored in the ensuing decades, and public knowledge of the program remained incomplete.

Academic interest in the subject revived in the early 2000s, and by April 2012 a series of international studies finally exposed the scale of the experiments, including the systematic infection of Chinese villages, the use of contaminated food and water supplies, and the in‑field testing of aerosol‑dispersed plague. Yet the identity of many of the individuals behind those operations remained elusive – until now.

The June 13, 2025, release of the Unit 1644 roster was the result of a sustained campaign by Katsuri, whose grandfather served as a medical officer in the unit, and Nishiyama, whose research on Japan’s wartime bio‑weapons has been cited by scholars worldwide. Their petition to the National Archives emphasised the moral imperative of confronting the past and argued that the families of victims – many of whom are still alive today – deserve official acknowledgement of the crimes committed. In response, the archives opened a sealed collection that included enlistment forms, transfer orders, internal memoranda on the procurement of Yersinia pestis cultures, and after‑action reports describing the outcomes of field tests in Hebei and Henan provinces.

The documents are chilling in their detail. One memorandum, dated November 1942, instructs the unit’s “bacteriological section” to increase the production of “type B” plague bacilli for “use in upcoming operations against enemy strongholds.” Another entry records the death of a laboratory technician after accidental exposure to an anthrax spore batch, noting in a terse footnote that “the loss is regrettable but does not affect the schedule of production.” A third file lists the names of civilians who were selected for “human inoculation trials” – a euphemism that, according to the researchers, signified lethal injection of live pathogens.

The public reaction in China has been immediate and visceral. Social‑media platforms are awash with outrage, with users denouncing the historical amnesia that they say has allowed Japan to “whitewash” its past. Posts repeatedly stress that forgiveness is not an option, that “forgetting history is betrayal,” and that the newly released evidence must be taught in schools to prevent a repeat of such atrocities. In Japan, the response is more muted but significant: historians and human‑rights activists have called for a parliamentary inquiry, while nationalist commentators have dismissed the documents as “war‑time records” that do not reflect the actions of the present.

Beyond the emotional resonance, the evidence has concrete political ramifications. For Beijing, the roster bolsters long‑standing claims that Japan has never fully reckoned with its wartime conduct, a point that routinely surfaces in diplomatic negotiations over trade, security and regional cooperation. For Tokyo, the disclosure adds pressure on a government that, despite recent apologies and compensation packages, continues to struggle with how to address the darker chapters of its history without appearing to undermine national pride. The timing could also influence ongoing discussions in the United Nations about historical justice and reparations, especially as other nations revisit their own colonial or wartime legacies.

Internationally, scholars see the archive’s decision as a noteworthy – albeit belated – step toward transparency. The linkage between Unit 1644 and Unit 731, once a matter of speculation in some Western circles, is now documented with primary source material that can be examined by historians worldwide. Legal experts point out that the newly surfaced records could, in theory, be used as evidence in future war‑crimes tribunals, although the passage of time and the death of most directly involved parties may limit practical outcomes. Nonetheless, the broader impact is clear: historical accountability can shape contemporary international norms, and the exposure of Japan’s biological warfare program reinforces the global imperative to forbid the development or use of such weapons.

For ordinary readers, the story is a stark reminder that the past does not stay buried simply because it is inconvenient. The names on the roster – whether they were fervent believers in a militarist ideology or reluctant conscripts swept into a program they could not control – are now part of an official record that confronts denial with documentation. The descendants who helped bring these files to light, especially Takeshobo Katsuri, have underscored a lesson that reverberates across generations: truth is a collective responsibility, and acknowledging it is the first step toward any genuine reconciliation.

As the archives continue to catalogue and release additional material, historians anticipate that more details about the scope of Japan’s germ‑warfare will emerge. Each new piece of evidence not only fills a gap in the war‑time narrative but also serves as a cautionary tale for the present – a reminder that science can be turned to cruelty when placed in the hands of a regime that values conquest over humanity. In the weeks and months ahead, the world will watch how governments, scholars and ordinary citizens respond to a truth that, for decades, was kept in the shadows. The hope is that, this time, the light will be long enough to keep such darkness from ever rising again.