Bạch Đằng River
The capture of the Mongol supply fleet at Vân Đồn along with the concurring news that General Trần Hưng Đạo had recaptured Đại Than garrison in the north sent the fast advancing Mongol forces into chaos. The Đại Việt forces unleashed guerrilla warfare on the weakened Mongol forces causing heavy casualties and destructions to the Yuan forces. However, the Mongols continued advancing into Thăng Long due to their massive cavalry strength, but by this time, the emperor decided to vacate Thăng Long to flee and he ordered the capital to be burned down so the Mongols wouldn't collect any spoils of war. The subsequent battle skirmishes between the Mongols and Đại Việt had mixed results: the Mongols won and captured Yên Hưng and Long Hưng provinces, but lost in the naval battles at Đại Bàng. Eventually, Prince Toghan decided to withdraw his naval fleet and consolidated his command on land battles where he felt the Mongol's superior cavalry would defeat the Đại Việt infantry and cavalry forces. Toghan led the cavalry through Nội Bàng while his naval fleet commander, Omar, directly launched the naval force along the Bạch Đằng River simultaneously.