Sō clan
On 19 June, 1419, the recently abdicated king Taejong of Joseon sent general Yi Jongmu to an expedition to Tsushima island to clear it of the Wokou pirates, using a fleet of 227 vessels and 17,000 soldiers, known in Japanese as the Ōei Invasion. After suffering casualties in an ambush, the Korean Army negotiated a ceasefire and withdrew on 3 July, 1419. In 1443, the Daimyō of Tsushima, proposed the Treaty of Gyehae. The number of trade ships from Tsushima to Korea was decided by this treaty, and the Sō clan monopolized the trade with Korea.