Bernard de Neufmarche, Lord of Brecon - Great research and the power of women to affect medieval succession

"By the time of his death around 1125, Bernard had established a flourishing borough around his castle of Brecon. Henry I had married Bernard's daughter Sybil to Miles Fitz Walter, the sheriff of Gloucestershire, in 1121 and passed a significant portion of Bernard's honour to him as a dowry, including Hay-on-Wye Castle.[20] According to Giraldus Cambrensis this was because Mahel de Neufmarché the son and heir of Bernard had mutilated the paramour of his mother. In vengeance his mother, Princess Nesta, swore to King Henry I that her son was illegitimate. Henry was therefore able by law and custom to pass over Mahel and give the land to his friend and confident Miles Fitz Walter with Bernard's legal heiress in marriage."

Very interesting!