In 1269, Trần Quốc Khang was appointed as commander in chief (thượng tướng quân) to govern the southern frontier province Nghệ An. Prince Tĩnh Quốc decided to build his palace there, which was so luxurious that the Emperor knew about its reputation. Ultimately Prince Tĩnh Quốc transformed his palace into a Buddhist pagoda which still remains today with the name Thông Pagoda. During the invasion of the Yuan Dynasty in Đại Việt, Trần Quốc Khang's son, Marquis Chương Hiến (Chương Hiến hầu) Trần Kiện surrendered to Kublai Khan's prince Toghan. He was one of the highest ranking defectors of the Trần Dynasty, just lower than Trần Ích Tắc, Trần Quốc Khang's younger brother. Before he could flee to northern border, Trần Kiện was killed in February 1285 by Nguyễn Địa Lô, house servant of Trần Hưng Đạo who incidentally was a son of Trần Liễu and thus a natural brother of Trần Quốc Khang.