Hwarang Knows No Retreat is Gwanchang. He is the sponsor of Min Jiwon's captain.
In the original Battle of Hwangsanbeol, he had his throat slit by Gyebaek, and the Kingdom of Silla eventually won the battle due to his sacrifice. However, in the recreation Battle of Hwangsanbeol, Kim Dokja summoned the constellation King Heungmu the Great, intervening in the battle, changing the course of events, and preventing his incarnation's death.[1]