On Dal, commonly referred to by Koreans as "On Dal the Brave", was a Goguryeo General and the husband of Princess Pyeonggang. A legend tells that he was unusually tall, his face was handsome, and he had a good heart. His family was poor, so he begged for his mother. Though of middle-class origin, he later married King Pyeongwon of Goguryeo's daughter Princess Pyeonggang and then become a general. He died bravely leading the Goguryeo garrison in 590 at Achasanseong Fortress during a battle against the Silla army.