Inside Unit 731 and Japan’s Human Experiments in WW2

From 1939 to 1945, the world witnessed the deadliest war in history, as over 30 countries wound together in acrimony, strife, and bloodshed, leading to a war that claimed the lives of more than 100 million people all over the world. History reveals that the war was replete with different subplots, each significantly ravaging our shared humanity.

But of all these battlefronts, the Pacific Theatre, hosting the most extended series of battles during WW2, stands tall as the epicenter of the action.

Historians recorded that Japan started the war when it launched an attack on Manchuria in 1931 and invaded China in 1937. This invasion was instantly followed by disturbances and upheavals that shook China’s very foundations, culminating in a civil war and famine that claimed the lives of over 63 million persons, lasting until China’s liberation in 1945.

Imperial Japan did unleash unspeakable terror on China during its occupation. Still, all these are nothing compared to the atrocities perpetrated in Unit 731 – the very center-point of Japanese biological warfare units that plunged the already genocidal war into newer depths of horror.

What started as a research and public health agency with a noble, innocent beginning descended into an abyss of terror when Unit 731 grew an assemblage for weaponized diseases that could have killed every living thing on earth multiple times over if deployed to its maximum strength.

This rather sordid shift in purpose was designed for the eternal suffering of captives as disease incubators and test subjects which very well served its purpose until 1945 when Unit 731 shut down operations.

But before then, Unit 731 had committed some of the most degrading and torturous human experiments in human history.

The main building of Unit 731

Frostbite Tests

Perhaps, assigning Yoshimura Hisato to Unit 731 marked the beginning of doomsday for the Chinese captives. Here was a physiologist with an uncanny obsession for hypothermia, whose curiosity had no limits and who had almost no regard for human life.

Attempting to improve on Maruta’s research on limb injuries, Hisato submerged the limbs of Chinese captives in water and ice and held them until the limb – arm or leg – had frozen with visible ice coatings on the skin. Eye witness accounts say the limbs sounded like wood when hit with a plank. But for Hisato, this was only the beginning. 

He attempted different methods to rewarm the frozen limbs as rapidly as possible. In some cases, he would douse the limb with hot water; other times, he would hold the limbs close to an open fire. And sometimes, he would leave the subject untreated overnight to examine how long it would take for the subject’s blood to break off the frost.

Maruta and the Throes of Vivisection

Established as a research unit, Unit 731 was preoccupied with investigating how disease and injury affect the fighting ability of armed forces. However, “Maruta,” an arm of the Unit, went rogue when it took up the research by a notch, breaking the defined bounds of medical ethics, though, at that point, it only observed injuries and disease courses on patients.

The project began with volunteers from the Army, but as the experiments scaled new highs and the supply of volunteers ran out, the Unit soon turned its attention to Chinese prisoners of war and captives. Consent became a thing of the past, and there was no limit to what researchers could do.

At this point, Unit 731 referred to their confined research subjects as “Murata” or “logs.” Needless to say, the study methods deployed for these experiments were highly dehumanizing.

Vivisection, one of the most common practices in those days, deserves special mention here. This was a process whereby human bodies were mutilated without anesthesia to conduct studies and experiments in living systems.

In those days, thousands of persons, primarily Chinese captives, elderly farmers, and children, who suffered diseases such as the plague and cholera, had their organs removed and examined.

This was mainly to study the possible effects of their various diseases before their body decomposes after death. In some instances, subjects had their limbs detached and reattached to another half of their body, while some had their limbs frozen, crushed, or cut off to study the spread of gangrene in the body.

When a subject’s body had exhausted its use, they would drive lethal injections into their body or shoot them even while some were buried alive. None of these Unit 731 subject captives survived this dehumanizing confinement, whether Chinese, Korean, Russian, or Mongolian.

Atrocious Weapons Tests

In every war, weapons superiority is a central talking point for superpowers. The Japanese knew this, only that they took it too seriously.

As the war raged, the effectiveness of weapons manufactured became a significant question and an area of interest to the Army. As part of efforts to determine the potency of their weapons, Unit 731 huddled captives together within a firing range.

It blasted shots at them from different ranges using Japanese weapons such as bolt-action rifles, Nambu 8mm, machine guns, grenades, and pistols. In assessing the varying levels of effectiveness, researchers compared wound patterns and depths of penetration to dying inmates and actual deaths.

Traditional weapons like knives, swords, and bayonets were equally studied, except in this case, the victims were usually bound. Unit 731 also tested flamethrowers on covered and open skin, while gas chambers were built at strategic unit facilities to expose test subjects to blister agents and nerve gas.

Victims were bound in one place as heavy objects dropped on them to study crush injuries, while test subjects were wound up and deprived of food and water to learn how long the average human can survive without water.

In most cases, these victims drank only seawater or were impaled with injections of mismatched animal or human blood to analyze the process of transfusion and clotting.

Prolonged exposure to x-ray sterilized and maimed thousands of research subjects while inflicting severe burns in cases where the emitting plates are miscalibrated or placed too close to the participants’ genitals, faces, or nipples.

Unit 731 also studied the effects of high G-forces on pilots and falling paratroopers. They loaded human beings into large centrifuges, spinning them at extremely high speeds until they lost consciousness or died, typically at 10 to 15 G’s. They found that young children were more tolerant of acceleration forces.

Syphilis Studies on War Captives

History has shown that venereal diseases have inflicted major disruptions on organized armies since ancient Egypt. In attempting to prevent similar occurrences, the Japanese military took an interest in studying the symptoms and treatments of syphilis.

For a start, doctors at Unit 731 infested test subjects with syphilis, withheld treatments, and observed the progress of the illness.

However, Salvarsan, a primitive chemotherapy agent and contemporary treatment in those days, was administered within a specified period to assess the side effects of the disease.

Male subject carriers of syphilis were asked to rape male and female captives to ensure the disease was effectively transmitted.

The infected prisoners were closely monitored to observe the onset and spread of the illness. Where the first exposure resulted in zero infection, more subjects were raped until the infection was established.

Rape and Systematic Pregnancy

You may consider the syphilis experiment far too outrageous, but it probably pales compared to the spate of rape and forced pregnancy that characterized Unit 731’s operations.

The most common instance includes female captives being raped and systematically impregnated so that trauma and weapon experiments could be carried out on them.

These women were advertently infected with life-threatening diseases, doomed to crush injuries, chemical weapons exposure, shrapnel injuries, and bullet wounds.

After this, Unit 731 doctors opened up the pregnant subjects and studied the effects of these injuries on the fetuses.

It appears the ultimate objective was to transpose the findings into contemporary medicine, but even if Unit 731 researchers had published these findings, the papers might not have survived the war.

Fleas and Plagues on Chinese Civilians

As time passed, it became clearer that Japan’s Unit 731 was driven by an ultimate mission to develop weapons of mass destruction by 1939, to ravage the Chinese people, and destroy Allied forces, if time permitted.

The Unit rounded up tens of thousands of captives caged across different facilities in Manchuria, which imperial forces had occupied for decades.

The Japanese infected these inmates with the most lethal virus and pathogens science has ever known. Prominent examples of such deadly pathogens include yersinia pestis, which causes the pneumonic and bubonic plague, and typhus, which the researchers systematically spread from one inmate to another to depopulate notable areas.

The doctors bred the most dangerous strains and monitored patients as they advanced through various stages, from symptoms to spread. When victims survived, they were shot, and the sickest were left to bleed on the mortuary table if they fell ill.

The doctors would take their blood would infect other captives, and the sickest from this group would be bled to transfect the deadliest strain to another group of prisoners.

Once, a member of Unit 731 pitched the idea that the sickest captives should be spread out on a slab with a line inserted into their carotid artery.

That’s not all – when the blood has been sucked out of their heart which would be too weak to pump more blood, a military officer will jump on the victim’s chest with his leather boots. The officer did this with so much force and vigor that it crushed the captive’s ribcage, and blood would spurt into a designated container.

One of the significant plagues bred by the Unit – plague bacillus – was built into a vastly lethal pathogen. The last set of subjects was exposed to an overwhelming huddle of fleas.

These fleas were packaged and sealed with clay bomb casings. On 4th October 1940, Japanese bombers released these casings, each containing 30,000 blood-sucking fleas that were initially exposed to the prisoners in a Chinese village called Quzhou.

According to eyewitnesses, the bombing was accompanied by fine crimson dust settling on different surfaces of the town and a succession of terrible flea bites that ravaged everyone present.

A series of eyewitness accounts agreed that at least 2,000 Chinese civilians died of the plagues foisted by these fleas, with 1,000 more deaths in a nearby village called Yiwu after sick railway staff carried the pathogen to this location. Unit 731 also employed anthrax to launch this attack, killing at least 6,000 people.

As the war tailed to an end, Japan tried to bomb America with the same fleas, but to no avail. But this was perhaps the beginning of the end for Unit 731 because by August 1945, Hiroshima and Nagasaki had been bombed, and the Soviet Army invaded Manchuria and annihilated the Japanese Army. The emperor then read his surrender memo over the radio and disbanded Unit 731.

The research records and reports were burnt, and all the data and information generated by the Unit in 13 years were equally destroyed.

Some researchers returned to everyday civilian life in Japan as if nothing had happened, with some venturing into academics and medicine.

Some quarters believe that vestiges of the experiment may have found their way into academia and may have played significant roles in building war and medical technologies today.

However, these ideas are mere conjectures that thrive on the possibility that bits of information from inside Unit 731 may have escaped the 1945 purge.

But here’s what we know for sure: World War 2 is such a deadly detour in human history, and at the very center of the Pacific Theatre in Manchuria, humanity was bent backward – a thousand times and over, and for 13 solid years.

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