In history there exist events so dark, so unspeakably horrific that they send shivers down our spines and fill us with a dread sense of disbelief. One such grim chapter of the Second World War is the creation and operation of Unit 731, a clandestine biological and chemical warfare research and development unit of the Imperial Japanese Army. Their activities were responsible for some of the most horrifying war crimes committed during the war.
Unit 731 was headquartered in the Pingfang district of Harbin, the largest city in the Japanese puppet state of Manchukuo (now Northeast China). Operating from 1937 until Japan’s surrender in 1945, it functioned under the guise of a water purification plant or lumber mill to the outside world. Yet within its walls, the facility played host to unimaginable horrors, including human experimentation and biological warfare research.
The extent of Unit 731’s activities did not truly come to light until after the end of the war, remaining one of Japan’s most closely guarded secrets during the conflict. While the true numbers may never be known, estimates suggest that tens of thousands of individuals, primarily Chinese, Korean, and Mongolian civilians, along with Allied POWs, were subjected to cruel and inhuman experiments at the hands of Unit 731.
Background of Unit 731
Unit 731 was the brainchild of Shiro Ishii, a highly ambitious and ruthless medical officer in the Imperial Japanese Army. In 1930, Ishii proposed the creation of a bio-warfare research division, building on Japan’s earlier research into biological weapons during its occupation of Manchuria. Ishii’s idea gained traction as Japan sought new ways to assert its dominance in Asia, particularly as its war with China intensified.
In 1936, Emperor Hirohito officially approved the formation of what would become Unit 731, originally named the Epidemic Prevention Research Laboratory. Under the leadership of Ishii, who was promoted to Surgeon General, the unit’s activities ramped up significantly following the outbreak of the Second Sino-Japanese War in 1937.
The initial aim of Unit 731 was to develop and weaponize biological agents that could be used against enemy populations, thus weakening resistance and bolstering Japan’s war efforts. However, the unit’s focus soon expanded to include research into various fields such as epidemiology, bacteriology, virology, and pathology, often through horrifyingly unethical means.
From its inception, the unit operated under a cloak of absolute secrecy, being so covert that even high-ranking Japanese officials were often unaware of its existence. This secretive nature was further exacerbated by the complete dehumanization of its victims, who were referred to as “maruta,” or logs, reducing them to the status of inanimate objects for dispassionate study.
What Did They Do in Unit 731?
The activities carried out in Unit 731 were nothing short of grotesque, designed not just to develop potent biological weapons, but also to unravel the limits of the human body’s resilience and resistance to disease, torture, and mutilation. All the research in Unit 731 was performed on live subjects, who were exposed to a wide range of pathogens and inhumane conditions.
Subjects were purposely infected with diseases like plague, anthrax, cholera, and syphilis, and their disease progression was meticulously tracked. When the researchers desired to examine the effects of the diseases on internal organs, vivisections were performed, often without anesthesia, in order to keep the infections from being altered by the death process.
Moreover, the unit conducted tests on how extreme conditions affected the human body. This included forced pregnancies, simulated strokes, heart attacks, and frostbite. The frostbite experiments were particularly cruel, where victims’ limbs were frozen, then thawed to study the rotting and gangrene process.
Beyond the vile experimentation, Unit 731 was also heavily involved in the operational deployment of bio-warfare. These operations involved the release of plague-infested fleas over Chinese cities, leading to outbreaks of plague and countless civilian deaths.
What Were the Worst Crimes in Unit 731?
Among the myriad atrocities committed by Unit 731, several stand out for their sheer horror and inhumanity. Vivisections without anesthesia were a regular occurrence in Unit 731. Captives, including pregnant women, were cut open while still alive, often without anesthesia, to examine the effects of disease on their organs.
Then there were the frostbite experiments, in which victims’ limbs were subjected to sub-zero temperatures until frozen solid, with attempts made to rewarm the afflicted area resulting in agonizing pain and horrendous injuries. In some instances, when limbs were struck with a short stick, they would emit a sound similar to that of wood, indicative of the extent of the freezing.
The forced pregnancies were another appalling aspect of Unit 731. Women were forcibly impregnated and then subjected to vivisections to study the effects of venereal diseases and other conditions on the mother and fetus.
The biological warfare attacks against civilian populations were further atrocious crimes of Unit 731. Fleas infected with the bubonic plague were dropped over several Chinese cities, leading to massive outbreaks. It is estimated that these operations may have caused around 400,000 deaths.
Finally, the complete dehumanization of victims, who were frequently referred to as “logs” and reduced to mere experimental tools, is a testament to the horrifying disregard for human life prevalent in Unit 731.
The Horrendous Legacy Left Behind
The legacy of Unit 731 is a chilling reminder of the depths to which humanity can descend in times of conflict. Despite the horrific nature of its activities, the existence of Unit 731 remained largely unknown until several decades after the end of the Second World War, and its legacy remains a contentious topic to this day.
After the war, the researchers of Unit 731 were not brought to justice. Instead, they received immunity in exchange for sharing their research data with the United States, contributing to a Cold War-era bio-warfare arms race. This act of pragmatism has been widely criticized for effectively condoning the brutal experiments conducted by Unit 731.
The refusal by the Japanese government to acknowledge the existence and activities of Unit 731 until the 1990s further compounded the issue, causing considerable strain on Japan’s relationships with China and Korea, where the majority of the victims originated. When the acknowledgment finally came, it was viewed by many as being too little, too late.