The Nanjing Massacre or the Rape of Nanjing was the mass murder of Chinese civilians in Nanjing, the capital of the Republic of China, immediately after the Battle of Nanking and the retreat of the National Revolutionary Army in the Second Sino-Japanese War, by the Imperial Japanese Army. Beginning on December 13, 1937, the massacre lasted six weeks. The perpetrators also committed other war crimes such as mass rape, looting, torture, and arson. The massacre is considered to be one of the worst wartime atrocities.

Nanjing is the capital of Jiangsu province in eastern China. It is a sub-provincial city, and a megacity. The city has 11 districts, an administrative area of 6,600 km2 (2,500 sq mi), and a population of 9,423,400 as of 2021. Situated in the Yangtze River Delta region, Nanjing has a prominent place in Chinese history and culture, having served as the capital of various Chinese dynasties, kingdoms and republican governments dating from the 3rd century to 1949, and has thus long been a major center of culture, education, research, politics, economy, transport networks and tourism, being the home to one of the world's largest inland ports. The city is also one of the fifteen sub-provincial cities in the People's Republic of China's administrative structure, enjoying jurisdictional and economic autonomy only slightly less than that of a province. Nanjing has been ranked seventh in the evaluation of "Cities with Strongest Comprehensive Strength" issued by the National Statistics Bureau, and second in the evaluation of cities with most sustainable development potential in the Yangtze River Delta. It has also been awarded the title of 2008 Habitat Scroll of Honor of China, Special UN Habitat Scroll of Honor Award and National Civilized City. Nanjing is also considered a Beta city classification, together with Chongqing, Hangzhou and Tianjin by the Globalization and World Cities Research Network, and ranked as one of the world's top 100 cities in the Global Financial Centres Index.