The third Mongol invasion was also defeated by the Đại Việt forces under the leadership of General, later Prince Trần Hưng Đạo. In 1287 Toghan invaded with 70,000 regular troops, 21,000 tribal auxiliaries from Yunnan and Hainan, a 1,000-man vanguard under Abachi, and 500 ships under the Muslim Omar (tiếng Việt: Ô Mã Nhi) and Chinese Fanji (according to some sources, the Mongol force was composed of
300,000–500,000 men). Kublai sent the veterans such as Arikhgiya, Nasir al-Din and his grandson Esen-Temur. The strategy of this invasion was different: a huge base was to be established just inland from Hải Phòng, and a large-scale naval assault mounted as well as a land attack. Trần Hưng Đạo withdrew from inhabited areas, leaving the Mongols with nothing to conquer. 500 vessels were prepared to bring provisions to Toghan's army. Borrowing a tactic used by general, later Emperor Ngô Quyền in 938 to defeat an invading Chinese fleet, the Đại Việt forces drove iron-tipped stakes into the bed of the
Bạch Đằng River, and then, with a small flotilla, lured the Mongol fleet into the river just as the tide was starting to ebb. Trapped or impaled by the iron-tipped stakes (some of which have been recently recovered and now being displayed in a Hanoi museum), the entire Mongol fleet of 400 craft was sunk, captured, or burned by fire arrows. This would later become known as the Battle of Bạch Đằng. Caught between the Champa and Đại Việt, Sogetu lost his life. The Mongol army retreated to China, harassed en-route by Trần Hưng Đạo's troops. The Yuan officers such as Abachi and Fanji died in bloody retreat and Omar was captured.
Mongol invasions of Vietnam - Wikipedia, the free encyclopedia