Vietnamese. ‘Stake’. Term for 150 to 300 mm wooden poles, which in the past were used in Vietnamese maritime warfare, e.g. in the 10th and 13th century naval battles at the Bach Dang (Bạch Đằng) River near Halong Bay (fig.), in present-day northern Vietnam. Large poles, sharpened and tipped with iron, were embedded in the water at the mouth of the river, forming a barrier of poles that reached just below the water level at high tide. As the enemy fleet appeared, the Vietnamese would sent out small, shallow-draft boats at high tide to provoke a fight with the invading fleet and then retreat upriver, drawing the enemy's fleet in pursuit. As the tide fell, the heavy war vessels were caught on the poles and lay trapped in the middle of the river, whereupon they were attacked by Vietnamese forces. Thus the Vietnamese, led by Ngo Quyen (Ngô Quyền), were able to defeat the invading forces of the Southern Han state of
China, in the first Battle of Bach Dang in 938 AD (fig.), and consequently put an end to centuries of Chinese imperial domination in Vietnam. In 1288 AD, the tactic was used again by Tran Hung Dao (Trần Hưng Đạo - fig.) in the second Battle of Bach Dang, in which the Vietnamese defeated the Mongol invading army on the Bach Dang River (fig.).