In 1170 he established the Cistercian monastery of Strata Marcella . He again supported the English in 1173 , and was present at the Council of Oxford in 1177 . He was the only Welsh prince who refused to support the efforts of archbishop Baldwin and Giraldus Cambrensis in 1188 to preach the Crusade , for which he was excommunicated. It would appear that he handed over the reins of government to his son, Gwenwynwyn , in 1195 , and retired to the monastery of Strata Marcella , where he d. in 1197 , and where he lies buried. His first wife was Gwenllian , daughter of Owain Gwynedd (mother of Gwenwynwyn ), and his second wife was a daughter of Rhys ap Gruffydd .

In the early years of his reign he excelled as a warrior , and it is as such that Cynddelw sings his praises, but at a later date, Gerald is to speak of him as one of the three princes in Wales who were conspicuous ‘ for the justice, wisdom, and moderation of their rule .’ The latter also mentions his eloquent tongue and his sagacity. Yet his fame as a fighter remained, even among the Normans , as can be seen from the ‘ Legende de Fulk Fitz Warin .’ It is this aspect of his career that the prince himself reveals in his ‘ Drinking-horn of Owain ’-a poem patterned on the ‘ Gododdin ,’ in which a number of fellow-soldiers are each addressed in turn as the horn goes round. It is the best portrayal which we have of the campaigning life of a Welsh prince , with the close comradeship existing between him and his chosen war-band, and the thrill of their life of high adventure. There is also extant (in Myv. Arch. , 192 and R.B.H. Poetry , 1395-6 ) a series of englynion sung by the war-band of Owain to their ‘circuit’ of Wales . The circuit, however, is of North Wales only.