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Unit 8604
Unit 8604
Unit 8604
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Unit 8604
Japanese: 波8604部隊, romanized: Nami Hachi-roku-rei-yon Butai
Guangzhou headquarters
Active1938–1945
Country Japan
TypeEpidemic Prevention and Water Purification Department
Garrison/HQNational Sun Yat-sen University, Guangzhou, China
Engagements

Unit Nami 8604 (Japanese: 波8604部隊), officially the South China Epidemic Prevention and Water Purification Department (Japanese: 南支那防疫給水部, romanized: Nan-shina Bōekikyū Suibu), was a disease research unit under the South China Area Army of the Imperial Japanese Army. This unit extensively and secretly researched biological warfare and other subjects through human experimentation during the Second Sino-Japanese War from 1938 to 1945.[1]: 307 

History

[edit]

Founded in Osaka, Japan in September 1938 as the Epidemic Prevention Department of the Twenty-First Army, this unit landed in Daya Bay with the Twenty-First Army in early October of 1938. It entered Guangzhou in late October and took the campus of the National Sun Yat-sen University School of Medicine as its headquarters.[2] The unit took its names of Unit Nami 8604 and the South China Epidemic Prevention and Water Purification Department in April 1939.[3]: 3  The unit was disbanded in August 1945 after the Japanese surrender.[3]: 223 

Organisation

[edit]

The headquarters of Unit 8604 had a General Affairs Division, responsible for logistics, personnel and financial management. The First Section was responsible for bacteriological research and consisted of the General Affairs Section, the Research Section, the Inspection Section, the Media Section, the Sterilisation Section, and the Animal Section, with a total of about 80 men, including 10 general and colonel officers and 7 Chinese labourers. The second class was engaged in research on epidemic prevention and water supply. The third class was responsible for research on the treatment of various infectious diseases. The fourth class was engaged in plague bacteria cultivation and anatomy. The class was located in a basement surrounded by barbed wire, isolated from the outside world, and everything was carried out inside. In the basement of the fourth class's building, many formalin-soaked corpses were stored, and the chief of the section performed autopsies every day. The fifth section was the equipment supply department.[3]: 6 

According to the colophon of the unit's name book, in addition to the Guangzhou Headquarters, branches were set up in various parts of Guangdong, as well as in Chuzhou in Anhui Province, Fujian Province, Guangxi Province, and Kowloon in Hong Kong.[3]: 24  In 1939, Unit 8604 had six branches, each staffed by 225 men and headed by a medic major. The locations of these branches included Nanning and Qinzhou in Guangxi, as well as three branches in Guangzhou and one in Foshan in Guangdong. In particular, the 12th Field Epidemic Prevention and Water Purification Department was based in Xijiang Village on the northern outskirts of Guangzhou, the original site of the Chinese Fourth Route Army's Field Hospital and Military Medical School.[3]: 21 

Biological warfare

[edit]

The unit engaged in bacteriological research, normally breeding 10,000 rats per month and producing 10 kilograms of plague fleas.[2]

In April 1943, Unit 731 and Unit 8604 had similar production capacities, each capable of producing 10 kilograms of plague-infected flea per month. After that, the Japanese records show that it had a smaller share of bacteria production.[4]

In 1944, production increased to 15 kilograms per month following an order to increase output. According to confessions of a Japanese soldier, the unit had produced deadly bacteria for use against Chinese soldiers and civilians. Local residents had observed Japanese soldiers collecting rats with military vehicles and transporting them in carloads to Unit 8604.[2]

150 kilograms were expected to be produced by Unit 731 of the Kwantung Army, 20 kilograms by Unit 1855 in North China, 30 kilograms by Unit 1644 in Central China, 10 kilograms by Unit 8604 in South China, 60 kilograms by Unit 9420 in Singapore, and 30 kilograms by the Army Medical School in Japan.[4]

On 24 June 1945, the United States bombed and destroyed five rat breeding sheds and plague cultivation facilities of Unit 8604 with 25 to 26 B-29 bombers.[4]

Nanshitou massacre

[edit]
Main article: Nanshitou massacre
Two soldiers of the unit in Guangzhou

According to a Japanese soldier of the unit, the Japanese invasion of Hong Kong from February to May 1942 resulted in a large number of Hong Kong refugees being forced to leave the city and flood upstream along the Pearl River into Guangzhou. Most of them were detained at the Nanshitou Refugee Camp and subjected to inhumane bacteriological warfare. The Japanese army sent planes to bring in Salmonella enteritidis (paratyphoid bacteria) from the Tokyo-based Army Medical School, and instructed the unit to put it into their food. The refugees unknowingly ingested the bacteria. Salmonella has a high mortality rate, and a succession of deaths ensued.[5]

See also

[edit]

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Unit 8604

View on Grokipedia
from Grokipedia
Unit 8604, also designated as the Nami Unit or Wave Unit, was a clandestine biological warfare research and development outfit of the Imperial Japanese Army, officially masquerading as the Epidemic Prevention and Water Purification Department. It operated primarily from facilities at National Sun Yat-sen University in Guangzhou, China, between 1938 and 1945 amid the Second Sino-Japanese War. The unit systematically performed lethal human experiments, including vivisections without anesthesia and pathogen infections on prisoners of war and civilians—predominantly Chinese—to advance offensive bioweapons capabilities such as cholera and plague dissemination. These efforts supported field applications of biological agents against Chinese populations in southern regions, contributing to broader Imperial Japanese Army germ warfare campaigns that inflicted mass casualties through engineered epidemics. Postwar disclosures, including 2025 releases of personnel rosters from Japanese archives, have substantiated the unit's structure, membership, and role in these atrocities, underscoring the program's integration with notorious counterparts like Unit 731.

Historical Context and Establishment

Pre-War Influences and Formation

Japan's biological warfare program originated in the early , driven by General Ishii Shiro's advocacy following his inspections of Western laboratories and amid escalating tensions with Soviet forces along 's borders, where intelligence reports heightened fears of enemy biological capabilities. The 1925 Protocol's prohibition on biological weapons in warfare, which had signed, paradoxically spurred defensive and offensive research as military planners anticipated asymmetric threats in prolonged conflicts, particularly after the 1931 invasion of exposed vulnerabilities to disease outbreaks in occupied territories. This foundational interest emphasized first-line epidemic control units as dual-use covers for weaponization studies, setting precedents for regional detachments. As the Second Sino-Japanese War intensified from July 1937, the expanded southward, capturing on October 21, 1938, to secure supply lines and counter Nationalist Chinese resistance. In response, the Army established specialized units to address purported sanitation needs while advancing biological research suited to tropical southern climates and scenarios. Unit 8604, codenamed the Nami Unit, was formally created on April 8, 1939, under the official designation of the South China Epidemic Prevention and Water Purification Department, headquartered in and integrated into Ishii Shiro's overarching network of epidemic prevention facilities. This formation aligned with the Army's broader strategy of decentralizing biological efforts beyond northern facilities like , enabling localized adaptation to southern operational theaters without central oversight delays, though initial activities remained preparatory amid ongoing territorial consolidation. The unit's structure drew directly from earlier models, prioritizing medical personnel recruitment and infrastructure setup disguised as initiatives to evade international scrutiny.

Initial Operations in Occupied

Unit 8604 was formally established on April 8, 1939, in , shortly after the Japanese occupation of the city on October 21, 1938, as part of the Imperial Japanese Army's expansion of capabilities in southern . Initial deployment involved transferring specialized personnel from and northern units, with the roster comprising doctors, bacteriologists, and support staff tasked with organizing covert operations under the official designation of the Epidemic Prevention and Department of the Area Army. This structure allowed the unit to integrate into occupied administrative frameworks while preparing infrastructure for disease-related research. Logistical preparations by mid-1940 included acquiring and adapting civilian facilities in , such as repurposing sections of local medical colleges and laboratories for secure storage and preliminary culturing operations, enabling rapid setup without drawing overt attention. These adaptations prioritized containment and scalability, drawing on pre-war Japanese expertise in handling transferred southward amid escalating conflict in . The unit's early phase emphasized resource consolidation, including procurement of equipment for and as a dual-use . As a sister unit within the Ishii Network overseen from , Unit 8604 coordinated with in for technology transfers, particularly in plague cultivation techniques and vector breeding methods, aligning southern operations with northern research goals to counter endemic diseases weaponized for regional denial. This collaboration facilitated shared intelligence on plague strains prevalent in subtropical climates, with initial exchanges documented through personnel overlaps and directive chains from the Epidemic Prevention headquarters. Such linkages ensured standardized protocols while adapting to local conditions in occupied and surrounding territories. Early activities centered on epidemic surveillance and control measures as a operational cover, involving field teams monitoring and documenting natural outbreaks of plague and other pathogens in occupied areas to establish baseline epidemiological data for future applications. These efforts, conducted from 1939 onward, included vaccination campaigns and quarantine enforcements that masked data collection on transmission dynamics and mortality rates, providing empirical foundations without immediate overt weaponization. By leveraging existing disease patterns in densely populated zones, the unit amassed records on over a dozen reported incidents in southern China, refining logistical models for scaled responses.

Organizational Framework

Command Structure and Key Personnel

Unit 8604's command structure mirrored the Imperial Japanese Army's specialized medical units, emphasizing bacteriological expertise under military oversight, with leadership roles filled predominantly by army physicians and officers from the Epidemic Prevention and Water Purification Department. The unit fell under the Area Army's operational chain, facilitating coordination with regional forces while aligning with centralized biowarfare directives from Tokyo's epidemic prevention apparatus. Colonel Shunji Sato served as the unit's chief from November 1941 to 1943, having been promoted to colonel in August 1941 and tasked with overseeing research and deployment activities in Guangzhou. Prior to Sato's tenure, the unit's formation in 1939 integrated medical officers experienced in pathogen handling, drawn from army medical corps, to direct experimental protocols without independent field command authority. Declassified personnel rosters released by Japan's in May 2025 detail a core staff of approximately 200-300 individuals, including bacteriologists, laboratory technicians, and administrative support personnel, underscoring the unit's reliance on specialized military talent rather than large-scale combat forces. These records highlight the hierarchical integration, where subunit directors reported to Sato or equivalent heads, ensuring alignment with broader Imperial Army biowarfare objectives across occupied territories.

Facilities and Operational Base in Guangzhou

Unit 8604 maintained its primary operational base in , Province, as part of the Imperial Japanese Army's Southern China Area Army structure. The unit operated under the official designation of the Epidemic Prevention and Water Purification Department, a euphemistic cover that facilitated the establishment of laboratories and support infrastructure masquerading as facilities. This disguise enabled the integration of specialized areas for handling infectious materials, including cultivation and containment zones, while projecting an image of routine sanitation efforts amid wartime occupation. Logistical operations centered on the Nanshitou district of , where the unit leveraged existing refugee detention infrastructure for and resource management. These sites, ostensibly for processing displaced populations from and , incorporated secured zones to isolate subjects and materials, supported by supply lines for medical and biological requisites coordinated with other Japanese military elements in southern . Security protocols emphasized operational secrecy through compartmentalization and the facade, minimizing exposure to Allied by aligning activities with civilian control narratives. Resource allocation included provisions for areas to support preliminary testing protocols, drawing from regional supply chains that funneled infected specimens and reagents from affiliated units across occupied territories. The base's infrastructure thus formed a self-contained hub, with modular facilities adaptable for and dissemination preparation, all sustained by the unit's documented personnel of approximately 860 members as of 1945.

Research Activities in Biological Agents

Pathogens Targeted and Experimental Methods

Unit 8604 primarily targeted , the causative agent of bubonic and , due to its high infectivity via flea vectors and potential for aerosol dissemination in humid subtropical climates like southern China. Other key pathogens included for , for , and agents of such as species, selected for their stability in water contamination and food-borne transmission routes suited to urban and rural environments in Guangdong province. These choices built upon earlier data from northern units like , adapting strains for warmer temperatures where flea proliferation and bacterial persistence were optimized. Experimental methods emphasized large-scale cultivation of plague vectors, infecting rats with Y. pestis via subcutaneous or respiratory , followed by breeding Xenopsylla cheopis fleas on the bacteremic hosts to achieve high rates—reportedly up to 90% in controlled infestations. and bacilli were mass-produced in nutrient broth fermenters, with viability tests assessing survival in diluted water simulants mimicking contamination. spores were sporulated under aerobic conditions and dried for storage, evaluating thermal resistance for bomb payloads. These techniques drew from Manchurian protocols but incorporated local strains for vector efficiency in tropical settings. Weaponization involved encapsulating infected fleas or liquid cultures in porcelain shells—thin-walled ceramic devices designed for aerial rupture and flea release—tested in sealed chambers for dispersal patterns and pathogen retention post-impact. Contaminated grain and water formulations were lab-assessed for bacterial load stability over 48-72 hours, using proxy indicators like colony-forming units to gauge dissemination viability without field release. Such methods prioritized scalability, with monthly outputs targeting kilograms of viable agent for potential integration into supply disruption strategies.

Human Subjects and Ethical Violations

Unit 8604 procured human test subjects, referred to derogatorily as maruta ("logs"), primarily from Chinese prisoners of war, convicted criminals, and local civilians captured in occupied southern . These individuals, estimated in the hundreds for the unit's operations from onward, were supplied through collaboration with the military police and local puppet regimes. Subjects were held in facilities near , with records indicating systematic to facilitate experimentation without ethical restraint. Experimental procedures involved deliberate via intravenous injection, forced oral ingestion, or aerosol exposure to pathogens such as plague, , and typhoid, followed by observation of progression. Vivisections were conducted without , entailing the live surgical removal of organs like lungs, livers, and brains to examine pathological changes , prioritizing direct causal analysis of mechanisms over any therapeutic intervention. Additional tests included exposure to extreme conditions, such as simulations or blood replacement with contaminated fluids, all designed to yield empirical data on lethality and dissemination potential. Mortality was integral to the research protocol, with subjects typically succumbing within days to weeks post-infection or , and no provisions for or documented in surviving records. A unearthed in in 1997, containing hundreds of remains consistent with experimental trauma, corroborates the scale of fatalities attributable to Unit 8604's practices. These methods mirrored broader biological programs but were tailored to subtropical pathogens prevalent in southern , reflecting a deliberate disregard for subject welfare in pursuit of weaponizable insights.

Deployment and Specific Incidents

Field Applications of Biological Agents

Unit 8604 supported Japanese military offensives in southern by producing biological agents for operational deployment, including plague-infected fleas bred in laboratory facilities in . By April 1943, the unit achieved a production capacity of approximately 10 kilograms of such fleas monthly, enabling their integration into efforts aimed at areas to incite outbreaks and erode resistance capabilities. These releases were conducted via aerial dispersal from , targeting populated regions to exploit disease transmission for strategic disruption without conventional engagement. Coordination with puppet regimes in occupied territories facilitated covert dissemination methods, such as introducing contaminated fleas or pathogens into wells, reservoirs, and agricultural crops, as evidenced by intercepted correspondence and operational logs from the period. This approach sought to amplify local epidemics while maintaining , leveraging collaborationist networks for ground-level execution in and surrounding provinces. Evaluations of these applications relied on contemporaneous outbreak surveillance, revealing inconsistent efficacy; for instance, southern China's humid climate often degraded flea viability and pathogen persistence, resulting in contained epidemics rather than widespread devastation, with mortality rates varying from dozens to hundreds per incident based on meteorological conditions and rapid quarantine responses. Such environmental limitations prompted iterative adjustments in dispersal techniques, though logistical challenges and enemy countermeasures frequently curtailed projected impacts.

The Nanshitou Refugee Detention and Mortality Event

In early 1942, following the Japanese capture of in , tens of thousands of Chinese refugees, primarily from , fled southward via the estuary and were intercepted and detained by Japanese forces at the Nanshitou camp in Guangzhou's Haizhu . The camp, ostensibly established for epidemic prevention and under the auspices of Unit 8604's official designation as the Epidemic Prevention and Department, served as a collection point where detainees underwent physical examinations amid ongoing refugee inflows estimated at up to 800,000 deportees from routed through Canton. This internment coincided with Unit 8604's intensified plague research, involving cultivation of bacteria and flea vectors, during a period of heightened biological experimentation in occupied . Mortality rates surged rapidly within the one-square-kilometer confines of the camp, with approximately 4,000 refugees perishing primarily from bacterial and viral infections introduced through live testing, compounded by due to inadequate provisions and overcrowding. While logistical failures such as shortages contributed to fatalities, primary causal factors traced to deliberate exposure included of water supplies and direct with plague and other agents, as the unit's personnel oversaw camp operations and blurred containment measures with applied research protocols. Estimates of total deaths vary, but Japanese archival rosters confirm the scale of human testing on detainees, with mass burials reported in the area without individual records. Japanese military documents, including a 1945 roster of 860 Unit 8604 members donated from the National Archives of , indicate direct oversight by unit medical staff, integrating refugee holding with dissemination trials that tested vectors under field-like conditions. Survivor accounts corroborate these records, describing systematic and outbreak acceleration beyond natural spread, suggesting intent to evaluate plague efficacy on civilian populations while masking operations as enforcement. This event exemplified the unit's dual role in research and control, with immediate fatalities driven more by engineered exposures than isolated hardships.

Postwar Reckoning and Revelations

Evidence Destruction and Initial Cover-Ups

As Japanese forces faced imminent defeat in , Unit 8604 personnel in followed directives common to the Imperial Japanese Army's network, systematically destroying research facilities, documents, and pathogen stocks to eliminate traces of human experimentation and weapon development. This included of logs detailing plague and studies, as well as disposal of infected materials like fleas and bacterial cultures, mirroring actions at primary sites such as Unit 731's Pingfang complex. Unit members scattered rapidly, with many commanders and researchers fleeing southward or repatriating to under assumed civilian medical identities, evading immediate Allied interrogations. Records that survived partial destruction were falsified to depict operations as routine initiatives under the unit's nominal " Prevention and Water Purification Department" guise, obscuring lethal field tests and vivisections. United States intelligence operations, prioritizing acquisition of biological data amid emerging tensions, abetted these efforts by offering immunity from prosecution to cooperating Japanese experts, including those linked to southern detachments like Unit 8604; this policy, endorsed by and the on April 17, 1947, barred public disclosure or trials without clearance, effectively burying initial evidence until fragmented logs emerged via private holdings.

War Crimes Trials and Suppressed Testimonies

The International Military Tribunal for the (IMTFE), convened from 1946 to 1948, prosecuted 28 senior Japanese military and civilian leaders for crimes against peace, war crimes, and , but allegations were peripherally addressed and largely unsubstantiated due to withheld evidence and focus on rather than operational units. Unit 8604's activities in southern received no specific , as tribunal prosecutors prioritized higher-level atrocities and lacked comprehensive documentation from dispersed regional programs. The Soviet Union's , held December 25–30, 1949, convicted 12 captured officers and scientists from and affiliated Manchurian detachments for manufacturing plague, , and other pathogens, as well as field deployments causing thousands of deaths, with sentences ranging from 2 to 25 years. However, these proceedings excluded Unit 8604 personnel, whose Guangzhou-based operations fell outside the Soviet-captured jurisdiction, resulting in no direct accountability for southern plague experiments despite overlapping methodologies. Post-trial, authorities interrogated numerous Japanese biological warfare experts, including those from units like 8604, but granted blanket immunity to most in exchange for detailed research data on human experimentation and weaponization techniques, a policy formalized by 1948 to counter perceived Soviet biological threats. This arrangement, documented in declassified U.S. Army reports, prioritized over prosecution, allowing figures such as subordinate commanders to evade charges while their testimonies—detailing dissemination scales and victim outcomes—were archived or redacted to prevent disclosure. Such suppressions stemmed from geopolitical imperatives, including the U.S.- security pacts initiated in 1951, which emphasized alliance-building against and deferred justice for wartime scientists integrated into postwar Japanese institutions. Defector accounts and captured logs hinting at Unit 8604's role in regional outbreaks were similarly sidelined, as Allied powers weighed evidentiary pursuit against the risk of alienating amid escalating hostilities. This causal linkage—trading accountability for bioweapons knowledge—perpetuated gaps in the historical record until later fragmented revelations.

Recent Archival Disclosures and Ongoing Research

In May 2025, Japan's publicly released 1945 personnel rosters for Unit 8604, alongside those of Units 1644 and 8609, detailing names, birthdates, addresses, family backgrounds, and prior military affiliations of approximately 860 members assigned to the Guangzhou-based unit. These documents, previously classified, provide empirical confirmation of the unit's organizational scale and medical-military personnel composition, enabling researchers to with wartime logs for verifying biowarfare operations rather than solely defensive prevention as officially designated. Scholar Seiya Matsuno donated a complete roster of Unit Nami 8604 to Chinese archives in 2025, facilitating public exhibition and further analysis that traces personnel overlaps with other bioweapons units like , underscoring coordinated offensive research into pathogens such as plague and anthrax for field deployment in southern . This disclosure has spurred ongoing archival cross-verification, revealing that Unit 8604's roster exceeds initial estimates of its size and includes specialists in whose post-war careers evaded scrutiny, challenging claims of isolated or purely prophylactic activities. Contemporary scholarly debates, informed by these rosters and declassified operational logs, reassess the unit's intent through causal analysis of deployment patterns, distinguishing offensive weaponization—evidenced by human vivisections and aerial pathogen dissemination—from contemporaneous Allied bioweapons programs (e.g., U.S. and British testing on ), which pursued similar agents without equivalent documented civilian targeting in . While mainstream narratives emphasize Japanese unilateral aggression, empirical review of rosters highlights mutual great-power incentives for biowarfare amid 1930s-1940s treaty breakdowns, though Unit 8604's integration of prisoner experiments for efficacy testing indicates prioritization of tactical offense over defense. Ongoing research leverages these records for epidemiological modeling of 1940s outbreaks in , correlating unit logs with incidence spikes absent natural zoonotic baselines, though source biases in state-influenced necessitate triangulation with Japanese primary documents.

References

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