William FitzOsbern, 1st Earl of Hereford
William FitzOsbern, 1st Earl of Hereford (c. 1011 – 22 February 1071) was a Norman noble and close adviser to William the Conqueror. He fought with William at the Battle of Hastings in 1066 and became one of the king’s most trusted allies.
In 1067, FitzOsbern was made Earl of Hereford and Lord of Breteuil, giving him large tracts of land in England and Normandy. He built and controlled many castles to secure Norman rule, including Carisbrooke Castle on the Isle of Wight and castles at Chepstow, Snodhill, Wigmore, Clifford, Berkeley, and Monmouth, as well as fortifications at Hereford and Shrewsbury.
FitzOsbern and his wife Adeliza de Tosny founded several religious houses: Lyre Abbey (La Vieille-Lyre) and Cormeilles Abbey, and Saint-Evroul Abbey. He was the son of Osbern the Steward and Emma of Ivry; his brother Osbern FitzOsbern was a cleric who later became Bishop of Exeter.
He and Adeliza had children: William of Breteuil, Roger de Breteuil, and Emma de Breteuil. After William became king, FitzOsbern remained a key administrator, ruling large areas in England and the Isle of Wight and helping to supervise the king’s campaigns in the southwest. He played a major role in suppressing the rebellion of Eadric the Wild and moving Norman influence into Wales, starting the Norman conquest of Gwent.
In 1070, Richilde, widow of Baldwin VI of Flanders, offered FitzOsbern marriage to gain control of Flanders. He led an army there but was defeated and killed at the Battle of Cassel on 22 February 1071.
This page was last edited on 2 February 2026, at 18:56 (CET).