“For the surgeons, it was a regular workday.” This is how, many years later, one of the doctors from Unit 731 recalled the autopsies performed on living humans in a Japanese military laboratory near Harbin during the Second World War.
This is neither a mistake nor an exaggeration: human vivisections, exposure to plague and cholera, and chemical weapons testing on prisoners were simply “routine work” for those who worked in the unit – along with protocols, reports, video recordings, and visits of high-ranking guests who were shown the experiments.
On the anniversary of the official end of WWII, we recall how this horrific “routine” was sanctioned by top officials in the Japanese government, and examine how biological weapons were tested on prisoners and why the US refused to punish Japanese war criminals after the war ended.
In 1926, a new emperor, Hirohito, ascended to the throne in Japan. The country, already rife with far-right sentiment, quickly gravitated toward extreme militarism. There were two reasons for this.
Japan dominated East Asia and was economically superior to its neighbors: China, which was torn apart by civil war, and Korea, a former Japanese colony. Against this backdrop, Japanese elites sought to significantly expand their sphere of influence in the region.
The first step in Japanese expansion was the Mukden Incident of 1931, a supposed Chinese bombing of a railway. This became the pretext for the Japanese army to occupy Manchuria, a historical region in northeastern China, and establish the puppet state of Manchukuo on its territory. Japan then hoped to subjugate the remaining territories of China.
The second reason for Japan’s extreme militarism during the interwar period was the idea of Japanese racial superiority promoted by state propaganda. Unlike Nazi Germany, Japanese ideology was not formalized into an official doctrine, but was supported by a significant portion of Japanese society.
A characteristic incident that vividly illustrated the situation in Japan at the time occurred in 1932.
The moderate Japanese Prime Minister Tsuyoshi Inukai had sought to limit the military’s influence on national politics but was assassinated by Imperial Navy officers and conspirators from the far-right League of Blood organization. Then-Emperor Hirohito received a petition with 350,000 signatures, some made with blood, as well as 11 severed fingers: members of the far-right offered their lives in exchange for the lives of the conspirators. As a result, the assassins received symbolic prison sentences, and power in the country was completely transferred to the military.
Japan was about to take the first step in the upcoming new world war.
In 1928, a brilliant graduate of Kyoto University, a young doctor and talented microbiologist, Shiro Ishii, traveled to Europe. He was described as a harsh and withdrawn man. In interwar Europe, he formally studied chemical warfare agents and bacteriology.
Ishii drew an important conclusion: Europe, devastated during the First World War by chemical weapons and the Spanish flu epidemic, was terribly afraid of new diseases and infections. The Geneva Protocol of 1925 banned the use of chemical and biological weapons in war. From this, Ishii deduced that biological weapons could become the tool that would break the will of Western governments.
Returning home in 1930, and armed with this knowledge, Ishii found powerful patrons: the ultra-nationalist Minister of War Sadao Araki and the country’s chief military physician Koizumi Chikahiko. The latter, who had been interested in chemical weapons since WWI, was impressed by the use of chlorine near Ypres in 1915 and hoped to fully develop this idea with Ishii’s help.
Together, in 1933, they obtained imperial approval to begin a secret project. They not only planned to develop biological weapons, but also initially planned to test them on living people.
Unit 731 was located in Manchuria, and not without reason. Having occupied this region, Japanese troops gained virtually unlimited access to the Chinese people, whom they viewed as a free resource for their inhumane experiments.
Another category of the unit’s victims were Soviet citizens, primarily ethnic Russians. Beginning in 1930, Japanese saboteurs began capturing Soviet citizens in border areas to obtain intelligence on the situation in the USSR.
Red Army prisoners of war captured during battles at Lake Khasan and the Khalkhin Gol river were also among the prisoners. They were considered missing in action for many years, but in reality, had been placed in the Hogoin concentration camp. If the prisoners refused to provide information about the military, political, or economic situation in the USSR, they were first tortured and then sent to Unit 731 for experiments.
China and the USSR were considered Japan’s primary adversaries in the upcoming WWII so Japanese doctors studied the use of biological weapons on representatives of these nations. It is estimated that the Chinese constituted approximately 70% of Unit 731’s victims, while Soviet citizens and a few Koreans, Manchus, and Mongols accounted for about 30%.
The project initially began as a small, secret laboratory in the Zhongma prison camp. But after several prisoners escaped, it became clear that the project needed better security.
Under the cover name of ‘General Directorate of Water Supply and Prevention of the Kwantung Army’ a real fortress was built in Pingfang, on the southern outskirts of Harbin. To make space for it, about 300 peasant houses were demolished, and in their place were erected barracks, laboratories, and a private airfield. The unit’s total staff numbered about 3,000 people.
With the outbreak of WWII, similar units were established in Japanese-occupied territories, including Singapore, the Philippines, Indonesia, Myanmar, and elsewhere. These units were part of the so-called Ishii Network, which numbered about 10,000 people.
The unit was divided into several specialized departments: one researched various viruses and infections, such as plague, typhus, anthrax, and cholera; another designed bombs for delivering biological weapons; and a third was engaged in the mass production of the pathogens themselves. Another department was responsible for “annihilating and writing off logs” – the term used to refer to prisoners subjected to inhumane experiments.
Initially, Unit 731 carried out experiments on POWs, anti-Japanese partisans, and common criminals. Initially, they were well-fed, given meat, fish, and sometimes even alcohol, all to ensure they were in good physical condition before the sadistic doctors began their experiments.
❗The editors warn that the description of the horrific experiments that took place in Unit 731 may shock readers.
Prisoners were infected with plague, anthrax, cholera, typhus, gonorrhea, and syphilis. They were also subjected to experiments to test their resistance to dehydration and frostbite. Essentially, the prisoners were subjected to conditions in which the Japanese army would operate in Southeast Asia and the Soviet Far East. These experiments simulated combat conditions more realistically than one could imagine.
For example, weapons such as grenades and bombs were tested on prisoners. To determine the optimal treatment for shrapnel wounds, prisoners were tied to posts and bombs and grenades were detonated at varying distances from them. Autopsies were performed on the dead, and those who survived were treated, but only to be killed in the next experiment. Flamethrowers were also tested on prisoners.
Prisoners, including infants born in the camp, were taken out into the cold and submerged in icy water. Rape and forced pregnancies with the aim of stydying the transmission of syphilis and other infections from mother to child were also frequent practices in the unit.
A separate horror was human vivisection – experimental surgeries and dissections of living people. These were done to study the body’s response in various conditions. A Japanese medical worker who witnessed this horror and had personally cut open a living person said that “for the surgeons, it was a regular workday.” Equally disgusting is the description of how, whenever the surgeons needed individual organs, such as the brain, they ordered the guards to find a suitable prisoner. The guards would smash the prisoner’s head with an axe, give the brain to the doctors, and send the body to the crematorium.
Prisoners were also subjected to prolonged starvation, placed in pressure chambers, crushed with heavy objects, electrocuted, buried and burned alive. The effects of phosphorus, phosgene, mustard gas, and other chemical warfare agents were also tested on the prisoners.
All these inhumane experiments were videotaped, meaning they weren’t isolated incidents perpetrated by specific sadists, but rather a routine and established procedure. Notably, some doctors later described with horror what they witnessed in Unit 731, while others, far from repenting, described the experiments performed on living people in scientific articles.
It’s also horrifying that the disembowelment of living people and other inhumane experiments were conducted for high-ranking guests visiting Unit 731 as a form of sadistic and inhumane entertainment.
The developments of the sadistic doctors from Unit 731 weren’t limited to laboratory use; they were actively used by the Japanese military in China. The Soviet Union first encountered Japanese biological weapons during the battle with the Japanese at Khalkhin Gol in 1939. At that time, Japanese troops secretly smuggled typhus vials on a passenger train and dumped them into border rivers, thus causing an outbreak of the disease on Soviet territory.
The Japanese military then carried out at least 12 attacks against Chinese cities. Specifically, they dropped plague-infected fleas from low-flying aircraft over the cities of Ningbo and Changde, causing an outbreak that claimed tens of thousands of civilian lives. During the war in China, the Japanese military also massively contaminated agricultural facilities, reservoirs, and wells. They also dropped contaminated food and clothing on territories unoccupied by the Japanese military under the guise of humanitarian aid; contact with these contaminated items led to infection and death. According to various estimates, at least 200,000 Chinese people died from plague, cholera, and anthrax spread by the Japanese military.
The Japanese also planned to attack the US with biological weapons. In December 1944, the Japanese navy began exploring the possibility of attacking cities in California, such as Los Angeles, San Francisco, and San Diego.
The plan was to launch aircraft from submarine aircraft carriers; the aircraft, manned by kamikaze pilots, would carry biological weapons developed by Unit 731, including plague, cholera, and typhus. The submarine crews were then expected to intentionally infect themselves and land on US shores.
However, this operation was initially suspended by the Chief of the Imperial Japanese Army General Staff Yoshijiro Umezu, and was subsequently cancelled after Japan’s surrender.
The Japanese military also planned to use biological weapons against the Soviet Union, but the rapid defeat of the Kwantung Army by Soviet troops thwarted these plans.
Realizing that they were on the brink of total defeat and seeking to cover up their crimes, the Japanese military destroyed the buildings of Unit 731 and its branches, laboratories, accumulated stockpiles of biological weapons, documents, and experiment results. About 300 remaining prisoners and 600 Chinese and Manchurian workers were exterminated.
This was standard Japanese military practice at the time. For example, on August 9, 1945, the day the USSR and Japan entered into war, Japanese gendarmes arrested and executed 19 Soviet citizens in the city of Hailar. Unlike the prisoners of Unit 731, those were ordinary people who were executed as potentially disloyal individuals.
So, when the Red Army units arrived at the site of Unit 731 a few days later, they found only an empty death camp. By that time, at least 3,600 people had died in horrific experiments, and hundreds of thousands others were killed by biological weapons developed by the Unit.
However, the end of militaristic Japan did not mean that Unit 731 was forgotten. Both the Soviet Union and the US knew that the Japanese military had conducted inhumane experiments, researched and used biological weapons. Naturally, the superpowers wanted two things: to obtain valuable materials from the sadistic Japanese doctors, and to punish the war criminals.
More precisely, it was primarily the USSR that wanted to punish the war criminals. After all, their experiments were also carried out on Soviet citizens. The Americans, however, assessed the situation differently.
The US needed to rebuild post-war Japan, which had fallen within its sphere of influence, so Emperor Hirohito, who had sanctioned the creation of Unit 731, was spared from a war crimes tribunal. The fates of the others who stood behind the creation of Unit 731 varied: Chikahiko, one of Ishii’s patrons, committed suicide in accordance with samurai tradition; another of his patrons, Sadao, spent several years in prison and was released in 1956.
Ishii’s fate is far more interesting. Shortly before the Soviet Army occupied Manchuria, Ishii evacuated with most of his staff and archives, first to Korea and then to Japan. It was there that the Americans found him after the end of WWII.
Initially, Ishii denied carrying out experiments on humans and the use of biological weapons, but the American military made him an offer he couldn’t refuse: complete immunity from prosecution in exchange for providing all data on biological weapons research based on human experiments.
As a result, Ishii and his associates prepared what the Americans themselves called an “absolutely invaluable” report on their work in human experimentation and the use of biological weapons. Ishii and other Japanese scientists then lived and worked peacefully under American supervision.
While the US concealed information about the activities of Unit 731 as much as possible, the Soviet Union held a public trial in Khabarovsk in 1949. Twelve high-ranking commanders and scientists from Unit 731 and its associated units were found guilty of war crimes and developing and using biological weapons, and served sentences in Siberian camps.
Japan reluctantly and slowly acknowledged the existence of Unit 731 and its horrific activities; archives containing the records of 3,607 Unit 731 personnel were only declassified in 2018.
On the anniversary of the official end of WWII, it’s worth remembering not just the abstract horrors of the past, but also the concrete facts: how a totalitarian machine placed its own interests above human life and universal moral laws. And how, after its defeat, its members received virtually no punishment for their crimes.
Many of the members of Unit 731 lived long and peaceful lives, pursuing successful careers in science, medicine, and business.
The only thing that can be done for the thousands of people who died in the camps of Unit 731 and the hundreds of thousands of victims of biological weapons developed there, is to remember the horrors perpetrated by this inhumane system and prevent them from ever happening again.
By Maxim Semenov, a Russian journalist covering international affairs, post-Soviet politics, and regional history.
By Maxim Semenov, a Russian journalist covering international affairs, post-Soviet politics, and regional history.
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