Bạch Đằng River
In 937, Đình Nghệ was assassinated by Kiều Công Tiễn, an formal military officer. Đình Nghệ's son in law and also his general, Ngô Quyền, mobilized his army to overthrow Kiều Công Tiễn. Công Tiễn called Liu Yan for support. Liu Yan then put his son Liu Hongcao in command of the expedition, granting him the titles "Jinghai jiedushi" and "King of Jiao", dispatching a fleet and sailing to the Gulf of Tonkin, headed inland up Bạch Đằng River, the water gate of Annam. Liu Yan himself led an additional force following his son's fleet.