The Nanjing Massacre (simplified Chinese: 南京大屠杀; traditional Chinese: 南京大屠殺; pinyin: N\xe1njīng D\xe0t\xfashā, Japanese: 南京大虐殺, romanized: Nankin Daigyakusatsu) or the Rape of Nanjing (formerly romanized as Nanking[note 2]) was the mass murder of Chinese civilians in Nanjing, the capital of the Republic of China, immediately after the Battle of Nanking in the Second Sino-Japanese War, by the Imperial Japanese Army.[2][3][4][5] Beginning on December 13, 1937, the massacre lasted six weeks.[note 1] The perpetrators also committed other war crimes such as mass rape, looting, and arson. The massacre is considered one of the worst atrocities of World War II.[6][7][8]

The Japanese army had pushed quickly through China after capturing Shanghai in November 1937. By early December, it was on the outskirts of Nanjing. The speed of the army's advance was likely due to commanders allowing looting and rape along the way. As the Japanese approached, the Chinese army withdrew the bulk of its forces since Nanjing was not a defensible position. The civilian government of Nanjing fled, leaving the city under the de facto control of German citizen John Rabe, who had founded the International Committee for the Nanking Safety Zone. On December 5, Prince Yasuhiko Asaka was installed as Japanese commander in the campaign. Whether Asaka ordered the Rape, or simply stood by as it happened, is disputed, but he took no action to stop the carnage.

The first Japanese troops reached the city on December 13, and faced little resistance. The massacre began the same day, with Japanese troops running entirely unchecked. Chinese soldiers were summarily executed in violation of the laws of war. Women and girls were raped en masse and looting was widespread.

Due to multiple factors, death toll estimates vary from 40,000 to over 300,000, with rape cases ranging from 20,000 to over 80,000 cases. However, most credible scholars in Japan, which include a large number of authoritative academics, support the validity of the International Military Tribunal for the Far East and its findings, which estimate at least 200,000 murders and at least 20,000 cases of rape.