Jang Bogo ruled the seas between China, Korea and Japan, tried to make his daughter a queen, and was stabbed over wine by an envoy who said he had fled the court

Jang Bogo was born, probably in 788, to a modest family on Wando off Silla's southwest coast. He served as an officer in the Tang army. In 828 he asked King Heungdeok for a garrison at Cheonghae to stop Chinese pirates enslaving Koreans, and the king agreed. World History Encyclopedia says the fortress held 10,000 soldiers. His fleet controlled trade between China, Korea and Japan. The Japanese monk Ennin sailed on one of his ships in 840. In 839 Jang attacked the capital and made Gim Ujing King Sinmu. Sinmu reigned about a year. Jang then pressed to have his daughter made consort of the new king, Munseong. The National Institute of Korean History calls the marriage plan the cause of his death and describes Jang as a humble man from an island. Yeom Jang, sent from the court, said he had fled the capital, won Jang's trust and stabbed him while they drank. Jang's deputy Yi Changjin rose against Yeom Jang and was put down. The Samguk sagi dates the killing to 846. The Institute argues for 841, citing Japanese and Chinese records and the marriage of the regent Kim Yang's daughter to Munseong in 842. In 851 the court abolished Cheonghaejin and forcibly moved its people inland to Byeokgolgun, now Gimje. The fortress site is on Jangdo islet off Wando^†.