He was a son of Owain Wan and thus a grandson of Caradog ap Gruffydd, the last Welsh king of Gwent.
In 1136 Morgan together with his brother Iorwerth murdered Richard FitzGilbert de Clare, the Anglo-Norman lord of Ceredigion, in an ambush during the Welsh revolt after the death of King Henry I.
He then captured Caerleon and Usk Castle,[2] thus gaining control of Upper Gwent and Llenfennydd.
Since the neighboring Norman Marcher Lords were themselves involved in the English civil war after the death of Henry I, he was able to hold on to his conquests.
He and his warriors fought several times as mercenaries in the service of Robert of Gloucester and Roger FitzMiles on the side of Empress Matilda,[3] including "as a terrible Welsh mob" together with Cadwaladr ap Gruffydd of Gwynedd and Madog ap Maredudd of Powys in the Battle of Lincoln.