The Battle of the Yalu River was the largest naval engagement of the First Sino-Japanese War, and took place on 17 September 1894, the day after the Japanese victory at the land Battle of Pyongyang. It involved ships from the Imperial Japanese Navy and the Chinese Beiyang Fleet.

The Beiyang Fleet was one of the four modernized Chinese navies in the late Qing dynasty. Among the four, the Beiyang Fleet was particularly sponsored by Li Hongzhang, one of the most trusted vassals of Empress Dowager Cixi and the principal patron of the "self-strengthening movement" in northern China in his capacity as the Viceroy of Zhili and the Minister of Beiyang Commerce (北洋通商大臣). Due to Li's influence in the imperial court, the Beiyang Fleet garnered much greater resources than the other Chinese fleets and soon became the dominant navy in Asia before the onset of the 1894–1895 First Sino-Japanese War. It was the largest fleet in Asia and the 8th in the world during the late 1880s in terms of tonnage.