From "The Matter of Wales: Epic Views of a Small Country" by Jan Morris, ISBN 0-19-504221-2, page 64:
The Normans in Wales turned thousands of free Welshmen into serfs, and drove thousands more out of their fertile flatlands into the mountains. They humiliated many an ancient house, and implanted arrogant dynasties of their own, Carews and Corbets, Turbervilles and Laceys, Cliffords and Mortimers and Baskervilles. They brutalized the landscape with their fortresses and savaged the people with their campaigns. William de Breos was popularly known as "the Ogre".

King Henry II granted the O'Carroll country (in Ireland) to Philip de Worcester and Theobald Fitzwalter, but his son, King John, sold the same country to William de Braosa. This led to complications. Fitzwalter, who was the first of the Irish Butlers, entered into an arrangement with de Braosa, explained in some charters, following.118

Charter of William de Braosa, AD1201 at Ormonde Archives, Kilkenny Castle:
William de Braosa, with the assent of his son, William, grants to Theobald Walter and his heirs five cantreds and a half of Munster, viz. the burgh of Kildelo, with half a cantred in which the burgh is situated, called Truoheked Maleth; Ely Kerrull (territory of Ely O'Carroll), one cantred; Elyohogarthy, one cantred; Ewurmun Ormond, one cantred. William de Braosa states that King Henry had granted these lands to Philip de Braosa, his uncle, and that King John, Henry's son, had restored them to him. By service of 22 knights Theobald Walter and his heirs are to hold them for ever by fee and inheritance, with all their appurtenances and appendages, with sach and soch, and thol and thean, and infangenetheof, judgment of water, iron and by combat, and with all liberties and free customs, etc. Walter de Braosa makes the present donation in presence of King John, in the 2nd year of his reign. Witness, Hubert, Archbishop of Canterbury; Roger, Bishop of St Andrews, Gilbert of Rochester and others.118

Charter of Theobald Walter:
Theobald Walter acknowledges that he and his heirs owe to William de Brahusa and his heirs the service of two and twenty knights for five and a half cantreds of land in Munster, viz., burgh of Kildelo, with half a cantred, called Truokehed Maleth in which it is situated; Ely Karuel (Ely O'Carroll) the whole cantred of: the whole cantred of Ely Hohogarthy: the whole cantred of Eruman, the whole cantred of Ared and Wetheni and the whole cantred of Owney O'Kathelen and Owetheni Oiffernan with all their appurtenances. Conditioned to be void if William de Brahusa shall not be able to acquire the land and services (in respect thereof) which William de Burgho (Burke) holds of Theobald Walter within the aforesaid five cantreds and a half. But if Theobald Walter makes good services, and de Brahusa succeeds in acquiring said lands, the said lands and services to remain to Theobald Walter and his heirs. Witness: Hubert, Archbishop of Canterbury, Henry de Castello, Tancred Archdeacon, Walter de Laci, William de Braosa, Phillip de Braosa, Walter de Braosa, sons of William de Braosa and others."118

William de Braosa, who executed the Charter in favor of Theobald Walter, was head of a family of high rank in Normandy and England, and also held possessions in Wales, where he severely repressed the natives. He entered into a contest with King John, mainly with reference to royal rents claimed from lands in Ireland. In this dispute his wife, Matilda, also became involved. John, while in Ireland in 1210 captured Matilda de Braosa and her eldest son, William, and sent them prisoners to England. There, by his orders, the mother and son were confined in a dungeon, and starved to death. William de Braosa, the father, disguised as a beggar, effected his escape to Paris, where he died.118

At his peak Lord of Bramber, Gower, Abergavenny, Brecknock, Builth, Radnor, Kington, Limerick and the three castles of Skenfrith, Grosmont (right) and Whitecastle.
William inherited Bramber, Builth and Radnor from his father; Brecknock and Abergavenny through his mother. He was the strongest of the Marcher Lords involved in constant war with the Welsh and other lords. He was particularly hated by the Welsh for the massacre of three Welsh princes, their families and their men which took place during a feast at his castle of Abergavenny in 1175. He was sometimes known as the "Ogre of Abergavenny".
One of the Normans' foremost warriors, he fought alongside King Richard at Chalus in 1199 (when Richard received his fatal wound). William received Limerick in 1201 from King John. He was also given custody of Glamorgan, Monmouth and Gwynllwg in return for large payments.
William captured Arthur, Count of Brittany at Mirebeau in 1202 and was in charge of his imprisonment for King John. He was well rewarded in February 1203 with the grant of Gower. He may have had knowledge of the murder of Arthur and been bribed to silence by John with the city of Limerick in July. His honors reached their peak when he was made Sheriff of Herefordshire by John for 1206-7. He had held this office under Richard from 1192 to 1199.
His fall began almost immediately. William was stripped of his office as bailiff of Glamorgan and other custodies by King John in 1206/7. Later he was deprived of all his lands and, sought by John in Ireland, he returned to Wales and joined the Welsh Prince Llewelyn in rebellion. He fled to France in 1210 via Shoreham "in the habit of a beggar" and died in exile near Paris.
Despite intending to be interred at St. John's, Brecon, he was buried in the Abbey of St. Victoire, Paris by Stephen Langton, the Archbishop of Canterbury, another of John's chief opponents who was also taking refuge there. His wife and son William were murdered by John, starved to death at Windsor Castle.