The battle took place on the field of Bạch Hạc, now located in Vĩnh Phúc province, northwest of Hanoi in mid-January 1258. The Mongol army defeated the Vietnamese counter forces of war elephants but failed to capture Trần Thái Tông as he escaped by boat, and the capital Thang Long, which was captured and sacked by the Mongols five days later
