Coc, i.e. tactical wooden poles, that are sharpened and tipped with iron, and which in the past were used in naval warfare. The ones seen here were retrieved from the Chanh and Bach Dang rivers, and date back to the 13th century Tran Dynasty. They were used in the second Battle of Bach Dang, in which the Vietnamese defeated the Mongol invading army on the Bach Dang River in 1288 AD (fig.). Today, these specific stakes are on display at the National Museum of Vietnamese History in Hanoi (fig.).