The early monastery was victim of multiple raids and finally ruined by William de Burgh in the early 13th century. To replace it, the local lord Owen O'Heyne (died 1253) founded the abbey of St. Mary de Petra as house for the Augustinian canons. The abbey is also attributed to Bishop Maurice Ileyan (died 1283) but the architectural evidence, according to Harold Leask, allows only the later added east range of the abbey to be associated with bishop Maurice. During the reformation this was granted to the Earl of Clanricarde.