Yangzhou massacre: The ten day massacre of the residents of the city of Yangzhou, part of the Transition from Ming to Qing.

The Yangzhou massacre in May, 1645 in Yangzhou, Qing dynasty China, refers to the mass killing of people in Yangzhou commanded by the Manchu general Dodo and carried out by Qing forces.

Yangzhou is a prefecture-level city in central Jiangsu Province, East China. Sitting on the north bank of the Yangtze, it borders the provincial capital Nanjing to the southwest, Huai'an to the north, Yancheng to the northeast, Taizhou to the east, and Zhenjiang across the river to the south. Its population was 4,559,797 at the 2020 census and its urban area is home to 2,635,435 inhabitants, including three urban districts, currently in the agglomeration.

The transition from Ming to Qing, also known as the Manchu conquest of China or Ming-Qing transition, was a decades-long period of conflict between the Qing dynasty, established by the Manchu Aisin Gioro clan in Manchuria, and the Ming dynasty in China and later in South China. Various other regional or temporary powers were also involved in this conflict, such as the short-lived Shun dynasty. In 1618, before the start of the Qing conquest, Nurhaci, the leader of the Aisin Gioro clan, commissioned a document titled the Seven Grievances, in which he listed seven complaints against the Ming, before launching a rebellion against them. Many of the grievances concerned conflicts with the Yehe, a major Manchu clan, and the Ming's favoritism toward the Yehe at the expense of other Manchu clans. Nurhaci's demand that the Ming pay tribute to address the Seven Grievances was effectively a declaration of war, as the Ming were unwilling to pay money to a former vassal. Shortly thereafter, Nurhaci began to rebel against the Ming in Liaoning, a region in southern Manchuria.

May 20 is the 140th day of the year in the Gregorian calendar; 225 days remain until the end of the year.