In Japan’s hellish “Unit 731”, where prisoners were raped during World War II to infect them with syphilis, prisoners of war were burned alive during flamethrower exercises, and children were given “anthrax chocolate” in cruel human experiments under the supervision of “Dr. Death”.

• WARNING: CONTAINS GRAPHIC CONTENT

Hidden behind the high walls of a brick building in northeast China, the atrocities committed by Unit 731 of the Japanese Imperial Army remained secret from the outside world for decades.

The facility, code-named the Kwantung Army Epidemic Prevention and Water Treatment Department, was actually a Japanese war camp where thousands of prisoners came but never left.

Inside, the inmates were subjected to sadistic human experiments that were unimaginable to most people – they were treated as human guinea pigs for some of the most heinous war crimes in history.

Innocent men, women and children were killed in the most cruel ways imaginable: dissected alive, infected with deadly viruses, raped and targeted with flamethrowers and even “plague bombs”.

Overseeing all these unspeakable crimes was Dr. Death of Unit 731 – Shiro Ishii – a charismatic surgeon and ultra-nationalist fanatic who is considered the architect of the now infamous atrocities of the death camp.

Army surgeon Ishii founded the Biological Warfare Research Unit in 1936 to conduct research into biological warfare, weapons capabilities, and the limits of the human body.

He did this with considerable government funding and the blessing of Emperor Hirohito, who approved of the policies and methods outlined to him and whose brother witnessed some of them firsthand.

Ishii arrived in Manchuria, present-day China, shortly after its occupation by occupying forces and set to work building his empire of death.

The site chosen for Unit 731 is a town called Ping Fan, 24 kilometers south of the regional capital Harbin. It is a far larger and more secure site than previous camps that were closed after their secrecy was compromised.

In the surrounding city, the Japanese occupiers did not allow the construction of buildings tall enough to catch a glimpse of the violence within the walls of the complex.

“None of the people here had any idea what the real purpose of this facility was,” said researcher Han Xiao. “It was the secret of all secrets – trains could only pass with the curtains drawn, and the air force shot down any plane that came too close.”

After its establishment, military police began searching for victims for the unit’s experiments – many of them were Chinese civilians, including children. The army also sent Russian, British and American prisoners of war there.

The inmates were deliberately kept healthy and fed rice, meat, fish and occasionally even alcohol so that their bodies were in good condition at the start of the experiments.

When an Imperial Army general inspected the unit, which had supposedly been created to support the Japanese war effort, he expressed his disgust at its activities and wrote about what he saw.

“It was said to be for national defense purposes, but the experiments were carried out with horrific brutality and the dead were burned in high-voltage ovens without leaving a trace,” he wrote in his memoirs.

The extent of the dehumanization was so great that the victims were called “Marutas” by their captors – Japanese for Logs.

The facility was also named Togo Unit, after Ishii’s favorite war hero, whose name he adopted as an alias, and served as a factory for his morbid fantasies.

According to historian Sheldon H. Harris, he and his colleagues used cruel methods to secure samples of certain organs for their experiments.

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“Whenever Ishii or one of his associates wanted to study the human brain, they ordered the guards to obtain a usable sample for them,” he wrote in his book Factories of Death.

“A prisoner was taken from his cell. Guards held him down while another guard smashed the victim’s head with an axe. His brain was removed and immediately taken to the laboratory.

“The body is then quickly taken to the pathologist and then taken to the crematorium for usual disposal.”

Vivisections were common practice, and former employees revealed decades later what they had seen – and even done themselves.

A former medical assistant at Unit 731, a farmer in his 70s who wished to remain anonymous, told the New York Times in 1995 the first time he cut open a living man.

“The guy knew it was over for him, so he didn’t resist when they led him into the room and tied him up,” he said. “But when I picked up the scalpel, he started screaming.”

“I cut him open from his chest to his stomach and he was screaming horribly and his face was twisted in pain. He was making this unimaginable noise, he was screaming so horribly. But then he finally stopped.

“For the surgeons, it was all part of their everyday work, but for me it left a lasting impression because it was my first time.”

The prisoners also had their limbs amputated and their organs removed before the depraved surgeons reattached their body parts – often in the wrong place – to observe the effect.

Another important part of Unit 731 was biological weapons experiments: Ishii and his henchmen bred deadly virus strains to wipe out the Chinese population.

Reports say that enough germs were created to kill everyone on earth several times over. 300 kilos of plague bacteria, 500 kilos of anthrax bacteria, and almost a ton of dysentery and cholera bacteria were produced every month.

The children were given chocolate laced with anthrax and biscuits contaminated with the plague, while the older prisoners were given dumplings and drinks contaminated with typhus.

Thirty teenagers from Harbin died after being given lemonade contaminated with typhus, according to a report in the Sydney Morning Herald that looked back at the horrors of the “Auschwitz of Asia.”

In another atrocity, men were infected with syphilis and then forced to rape other prisoners. The stated purpose of the torture was to find out how the disease was transmitted.

Women were forcibly impregnated so that they and their babies could be used in these experiments.

While babies were being born in Unit 731, all of the hundreds of prisoners who were still alive when Japan surrendered at the end of the war were murdered and buried while the Imperial Army tried to cover up their crimes.

Although former commanders, sworn to secrecy, were aware of the brutality of their own operations, many said they received no response while conducting those operations.

Sakaki Hayao, head of the Lin Kou branch of Unit 731, described an “extremely cruel” experiment conducted at the Anda Field in his testimony before the Special Military Tribunal in Shenyang in 1956.

Hayao said he saw people tied to wooden posts and exposed to the anthrax parasite through bombs filled with anthrax bacteria dropped from airplanes or detonated at close range.

The cruel experiment was carried out just months before Japan’s surrender. “It was a particularly brutal act,” he said.

Three days after the atomic bomb was dropped on Nagasaki, soldiers were ordered to bury the burned bones of murdered prisoners in order to cover up the unit’s crimes.

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In August, Soviet troops invaded what was then Manchuria and the members of Unit 731 retreated to Japan. Many of them never revealed their crimes and led relatively normal lives afterwards.

Particularly disturbing are the consequences that many of these cruel experiments, unique in the history of science, have had for today’s medical knowledge.

Some of the experimental data obtained from human subjects represented advances in modern medical understanding.

Ishii was reportedly particularly proud of Unit 731’s discoveries regarding the mechanism of frostbite.

These were made by tying people to posts at temperatures of -20 degrees and dipping their limbs in ice-cold water.

The effects of various remedies were tested on their frozen limbs. The sick surgeons also heated them up, causing pain, and tested the effects on victims, some of whom were only three years old.

General Okamura, a friend of Ishii, proudly noted in his memoirs: “I did not know the details of his medical advances, but after the war Ishii told me that his work had led to more than 200 patents.”

When the extent of what was going on there finally came to light, the Americans helped cover up the program in exchange for some of the data it contained.

The conviction of his crimes meant that Ishii was able to live out his final years in peace, despite all the pain and death he had caused and overseen – he died of throat cancer in 1959.