In the Nanking massacre (or Rape of Nanking) the Japanese military murdered 100,000 to 300,000 Chinese after conquering the city of Nanjing (then called Nanking in English, just as Beijing was called Peking.)
It was a war crime committed by the Japanese military during the Second Sino-Japanese War. The Japanese army committed atrocities against the capital of Nationalist China, famously murder and rape. The death toll is disputed, but most estimates give a total of 100,000 to 300,000 soldiers and civilians killed.  
- In December of 1937, the Japanese Imperial Army marched into China's capital city of Nanking and proceeded to murder 300,000 out of 600,000 civilians and soldiers in the city. The six weeks of carnage would become known as the Rape of Nanking and represented the single worst atrocity during the World War II era in either the European or Pacific theaters of war.
- In addition, the notorious Comfort Women system was introduced which forced young Chinese women to become slave-prostitutes, existing solely for the sexual pleasure of Japanese soldiers.
Adam Jones wrote:
- A conscious attempt has been made by "revisionists" in Japan to deny or downplay the involvement of the Japanese military in massive atrocities during World War II. In September 1986, the Japanese education minister, Fujio Masayuki, referred to the Rape of Nanking as "just a part of war." In 1988, a 30-second scene depicting the Rape of Nanking was removed from Bernardo Bertolucci's The Last Emperor by the film's Japanese distributor. In 1991, censors at the Ministry of Education "ordered textbook authorities to eliminate all reference to the numbers of Chinese killed during the Rape of Nanking because authorities believed there was insufficient evidence to verify those numbers" (Chang, The Rape of Nanking, p. 208). And General Nagano Shigeto, a Second World War veteran appointed justice minister in Spring 1994, told a Japanese newspaper that "the Nanking Massacre and the rest was a fabrication." 
- Encyclopaedia Britannica. Nanking Massacre
- Basic Facts on the Nanjing Massacre and the Tokyo War Crimes Trial
- The History Place - Genocide in the 20th Century