Whitland Abbey was originally a Cambro-Norman foundation, but soon came under the control and patronage of Rhys ap Gruffudd, Prince of Deheubarth. It is related in the Welsh annals that Cadwaladr, brother of Owain Gwynedd, Prince of North Wales, during the disputes which arose between him and his nephews, the sons of Owain, entrusted the custody of his newly erected Cynvael Castle to the abbot of Ty Gwyn ar Taf, who defended it with obstinate valour against the assaults of the young princes by whom it was besieged. After a determined resistance, protracted till the walls of the castle were beaten down, and the whole of the garrison either slain or wounded, the abbot effected his escape from the ruins, through the assistance of some friends in the camp of the enemy, and retired into his monastery.