William de Braose appears in The Chronicle of Battle Abbey as one of the early benefactors.
In those days also a powerful man among the king's barons, William, surnamed 'de Briouze', gave to the church of Battle in the county of Sussex and in the rape and borough of Bramber, eight messuages, and three others in Shoreham, free and quit, of his own demesne, and besides these, a hide of land in Shoreham as well, to be held for ever without claim, and besides, one hundred ambrae of salt annually, and also ten measures of wine which the abbot of Fecamp paid him each year for a certain land he held from him, Warminghurst near Chancton. And on behalf of a knight of his, named Hanselin, he conceded another hide of land called Erringham, free in the same way. And at the same time another knight of his, called Ralph son of Theodore, out of his own demesne, with the assent and confirmation of his lord William de Briouze, gave another hundred ambrae of salt to the church. Further, one of the men of William de Briouze, Tetbert by name, won over by the reports of virtue and sanctity, longed to undertake a monastic conversion. He brought himself, dedicated, to Battle and with the assent and confirmation of his lord, brought with him, free and into the eternal possession of the church, his land, namely one hide of land at Chancton in Heregrave, which is called Wulvrun-hide. All of which Philip de Briouze assented to and confirmed in the presence of his father William. And William conceded, according to the liberties and royal dignities of the church of Battle, that the burgesses he gave might buy and sell within their houses freely, without claim and without toll, except on market-day, when it is customary to transact business in public.