[1] He was a minor Norman lord who rose to power in the Welsh Marches before successfully undertaking the invasion and conquest of the Kingdom of Brycheiniog between 1088 and 1095.
[3] His ancestors on his mother's side had founded the town of Auffay south of Dieppe on the Scie, while his paternal grandfather, Turquetil (possibly known as Turchetil d'Harcourt), had served the young William II of Normandy as a guardian and was killed in that capacity.
All of Bernard's estates lay in the valley of the River Wye and along an old Roman road which led from Watling Street to Y Gaer and on into Brycheiniog.
[10] Bernard escaped without recorded punishment and the king probably conceded the marcher lords the right to expand their lands by conquest at the expense of the Welsh buffer kingdoms of Brycheiniog, Morgannwg and Gwynllwg.
Before the end of the year, though, he had captured Glasbury, for he issued a charter for lands near that place to the abbey of Saint Peter's at Gloucester (autumn 1088).
In 1088 the king, William Rufus, confirmed a previous charter of Bernard's stating that he had already made an exchange "within his lordship of Brycheiniog" at Glasbury.
Bronllys Castle may not have been built until 1144, when Roger Fitzmiles, Earl of Hereford, is first recorded granting it as a five-knight's-fee mesne barony to Walter de Clifford, son of Richard Fitz Pons.
According to much later accounts and reconstructions, of dubious accuracy but which contain some references to verifiable history, the king of Brycheiniog, Bleddyn ap Maenarch, allied with the king of Deheubarth, Rhys ap Tewdwr, in 1093 (or perhaps 1094) and tried to attack the forces of Bernard which were building a castle at Brecon on the Usk and Honddu in the centre of a great plain in his kingdom where several Roman viae met.
The Welsh Bruts simply state that "Rhys ap Tewdwr, king of Deheubarth, was slain by the Frenchmen who were inhabiting Brycheiniog."
Brycheiniog was unaffected and the Normans of that region launched a counterattack from Ystrad Tywy and Cantref Bychan which devastated Kidwelly and Gower but did not put down the revolt.
[15] In 1095 it spread to Brycheiniog and the Welsh of the countryside, allied with their compatriots of Gwynllwg and Gwent took back control of the province while the Normans were forced into their fortified centres.
Among the castles possibly built during Bernard's lordship to defend the entrances to Brycheiniog from the southeast were Tretower, Blaen Llyfni (not attested before 1207–1215), and Crickhowell.
Henry was therefore able by law and custom to pass over Mahel and give the land to his friend and confidant Miles Fitz Walter with Bernard's legal heiress in marriage.