Princess Joan was the daughter of King John, though she was illegitimate. In 1205 she married a man named Llewylyn ap Iorwerth, the master of Gwynedd. She made peace between her warring father and husband. She tried to maintain the same peace in other times, between Gwynedd and other lands. Little else is known of her life except that she had a son named Dafydd. Joan died in 1237.