During World War II, Japan fought with such brutality that even today Japanese scholars and diplomats have a hard time admitting these atrocities actually happened.

World War II struck devastating blows everywhere it took place, but the Pacific Theater was where nations fought the longest campaigns of the war and witnessed some of the most gratuitous cruelty in history.

Between 1937 and 1945, the Empire of Japan reached out into a dozen countries with what appeared at first to be an unstoppable military machine. What that machine did after the conquest, when it had unlimited civilian lives to play with, was often so barbarous, even modern Japanese society has yet to come to grips with it.

Japanese War Crimes: The Rape of Nanking

World War II began in China. The Japanese decision to occupy and annex Manchuria in 1931 set the ball rolling for everything that followed, including the U.S.-led oil embargo that was the proximate cause of the Japanese attack on the South Pacific and the war that followed.

The first shots of this war were fired in 1937, when the Empire of Japan launched a full-scale ground invasion of China in an effort to permanently crush Chinese resistance to Japan. Within months, the Nationalist capital of Nanking fell to the Japanese, and what followed has gone down in history as one of the worst wastes of human life on record: The Rape of Nanking.

Starting around December 13, 1937, and continuing for more than six weeks, Nanking suffered as few other cities in history ever have.

The Japanese, looking at the 90,000 captives as an opportunity to train their own soldiers in brutality, transported them out of the city for executions, the more brutal the better. They marched Chinese soldiers into designated killing fields. There Japanese officers and enlisted men shot, stabbed, and beheaded the Chinese in an attempt to condition them out of having human pity for a fallen enemy.

When the supply of POWs ran thin, the Japanese turned on the city’s 600,000 civilians, whom the retreating Chinese Nationalists had prevented from fleeing. In the orgy of rape and murder that followed, which saw babies run through with bayonets and pregnant women sliced open with swords, as many as 300,000 people may have died.

Things got so bad that the 22 Westerners remaining in Nanking organized a “safety zone” near the port, under the control of a German Nazi, of all people, named John Rabe.

The Rape of Nanking was such a horrific event that Japan has yet to fully acknowledge or apologize for it. For one, official Japanese estimates place the number of dead closer to 50,000.

Even now, nearly 80 years later, this refusal to take responsibility for the first major war crime of WWII remains a stumbling block in closer diplomatic and trade relations between the two countries.

Germ Warfare

We’ve already brought you the story about Unit 731, the Japanese germ warfare division that worked for more than ten years to weaponize some of the worst diseases that have ever afflicted mankind, but you may not have the sheer scope of the project in view.

Founded in 1931 as a normal army medical unit, by 1935 the team was stockpiling supplies of bubonic plague, anthrax, and cholera in forms that were distressingly easy to deploy against civilians.

In just a single attack in Manchuria, the Japanese dropped aerial bombs filled with sawdust and plague-infected fleas over population centers. This was partly a terror bombing against territory that the Japanese already controlled, and partly a test of the weapon’s effectiveness.

When the bomb casings split open in the air, the fleas fell unharmed to the ground and began biting people, infecting their blood with a strain of Yersinia pestis that had been bred for greater virulence by being passed through multiple generations of Chinese and Korean prisoners.

Poring over population figures before and after the war, the Chinese government now estimates that this one attack may have killed nearly 600,000 people in the weeks following the drop. Unit 731’s other activities may have killed another half a million or so innocent people before the end of the war.