 Trần Ích Tắc had already surrendered to the Yuan was willing to lead a Yuan army into Đại Việt to take the throne.In 1287, a Yuan army commanded by Toghan moved southwards from Guangxi and Yunnan in three divisions led by generals Omar, Zhang Wenhu, and Aoluchi.The army was complemented by a large naval force that advanced from Qinzhou, with the intent to form a large pincer movement against the Trần dynasty.