William de Braose had participated in the Norman conquest of England.
He had been rewarded with the feudal barony of Bramber in Sussex and smaller holdings in Dorset, Wiltshire, Berkshire and Surrey.
Philip de Braose conquered the Welsh borderlands at Builth and New Radnor and established new Norman lordships over them.
He supported King Henry I (1100–1135) against the claim to the English throne made by his elder brother Robert Curthose, Duke of Normandy, but then in 1110 he revolted against Henry, who then confiscated his estates.
He regained his lordships and lands in 1112 and was thereafter able to retain them, but in 1130 settled them intact onto his eldest son William de Braose, 3rd Lord of Bramber.