From c1173 to 1230 successive fathers, sons, and younger brothers called de Briouze were feudal lords of Abergavenny. William de Briouze, the first of them, who derived his name from his lordship of Briouze in Normandy, married the sister and coheir of the 2nd Earl of Hereford (also daughter of 1st Earl) mentioned above, which seems to account for his coming into possession of a lordship in that part of the Welsh marches. [Burke's Peerage]
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William de Briouze (e), Lord of Briouze in Normandy, and of Bramber, Sussex, son and heir of Philip de Briouze, be Aenor, daughter and heir of Juhel son of Alvred, Lord of Barnstaple and Totnes. He married, in or before 1150, Bertha, 2nd sister and coheir of William of Hereford being daughter of Miles of Gloucester, 1st Earl of Gloucester. Sheriff of Hereford, Easter 1173-75, at which earlier date probably he already possessed the Lordship of Over Gwent. He was living in 1179. [Complete Peerage I:21-2, XIV:6, (transcribed by Dave Utzinger)]
(e) Briouze-Saint-Gervais (formerly Braiose), arrond. of Argentan, dept. of Orne. His descendants spelt the name Brewes. In some 25 early references to this name, not in charter latin, it appears as Breouse, Breuse, or Brewys (the last of which still exists as a surname), but never as Braose, the form adopted in peerages, for which it seems doubtful if there be any good authority.
Note: The above text "1st Earl of Gloucester", which was part of a correction in CP XIV:6, is a mistake; Miles was Earl of Hereford.
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William was very fortunate in his marriage to Berta. All of her brothers died young without heirs, so she brought a number of important lordships to the de Braoses in 1166. These included Brecon and Abergavenny. William became Sheriff of Hereford in 1174. His interest in Sussex was maintained as he confirmed the grants of his father and grandfather for the maintenance of Sele Priory and extended St Mary's, Shoreham.
See St Mary's, Shoreham, Sussex.
William m. Berta, dau. of Milo de Gloucester, Earl of Hereford, and co-heir of her brother, William, Earl of Hereford, by whom he acquired Brecknock, with other extensive territorial possessions. He had two sons, William and Reginald, and was s. by the elder. [Sir Bernard Burke, Dormant, Abeyant, Forfeited and Extinct Peerages, Burke's Peerage, Ltd., London, 1883, p. 72, Braose, Baron Braose, of Gower]