Bermingham, Peter (Piers, Feoras) de (d. 1254), lord of Tethmoy, Dunmore, and Tireragh, was perhaps a son of Robert de Bermingham, who about 1172 was granted lands in Offaly by Strongbow (qv) (Richard fitz Gilbert de Clare). His family were vassals of the Geraldines, with whom they had established marriage connections.
Before 1234 Peter (or Piers) de Bermingham held Tuath dá Muighe (Tethmoy) of Maurice FitzGerald (qv), justiciar of Ireland, who was related to him. That year Peter sided with Maurice and Richard de Burgh (qv) in suppressing the rebellion of Richard Marshal (qv), and so gained royal favour. In 1235 he took part in the justiciar’s campaign in Connacht with Richard de Burgh, Walter de Ridelisford, and the earl of Ulster, Hugh de Lacy (qv). De Burgh ensured that his followers were generously rewarded; Peter, who had already been given the barony of Dunmore in Co. Galway, witnessed the grant of the five Sligo cantreds to de Lacy, and duly received a sub-grant of Tireragh in Co. Sligo from the latter.
Ten years later Peter accompanied Maurice FitzGerald, whose Anglo-Norman army was supplemented by an Irish force under Fedlimid Ó Conchobair (qv), king of Connacht, on campaign in Wales. In 1249 Peter, by this time known to the Irish as Feoras (a Gaelic form of Piers), had custody of the lands and castles of the younger Richard de Burgh during the minority of the latter's brother and heir, Walter (qv). Áed (qv), son of Fedlimid Ó Conchobair, leading a revolt against the English in Connacht, routed a party of Peter's horsemen near Sligo castle. Following this skirmish, Ó Conchobair's men killed one of Peter's sons, who was apparently named Gerald (Geróitín; ALC). Áed then plundered Tireragh, already at this early date called Crích Mhic Fheorais in Irish sources. The revolt was quelled by the intervention of Maurice FitzGerald and by Fedlimid Ó Conchobair's regaining control of the Irish nobility in the region.
Peter de Bermingham died near Cashel in 1254; in recording the event the Annals of Loch Cé styled him ‘Piers Pramister, lord of the Conmaicne of Dunmore’. He left three sons; James (fl. 1280), who succeeded to Tethmoy and Dunmore and was the father of Peter de Bermingham (qv) (d. 1308), Meiler (fl. 1264), who built Athenry castle and founded a Dominican convent there, and Maurice. Peter's descendants in Connacht adopted the patronymic Mac Fheorais (Corish).