In 1208, King John always on the lookout to increase his wealth, had devised a new money making scheme. His plan was to impose huge taxes on the barons for their land holdings, to blind the clergy and to confiscate all church property. In a rare moment of retrospection, John became concerned that the barons and the pope might not see the merit of this scheme. To ensure the full loyalty of his barons, John ordered them to provide him with hostages.
Matilda de Braose answered the kings messengers that she would not give her sons as hostage to the king, reasonably pointing out that the king had a habit of murdering people, including his own nephew, Arthur. The king, enraged that a woman should have made such a reply immediately confiscated all the de Braose property, including Bramber and Knepp castles and ordered the family captured.
Forewarned, the family fled to Ireland, but John sent forces to Ireland in pursuit of William de Braose and other barons. After a siege at Meath and pursuit to Scotland, Matilda de Braose and her son William were captured by John's forces. They were returned to England in chains and imprisoned in Windsor castle. John had offered Matilda de Braose her freedom and a pardon for her husband in exchange for forty thousand marks. Either unwilling or unable to pay, Matilda refused. John starved Matilda and her son to death in 1211. William de Braose the elder had escaped to Corbeil, France where he died in exile in 1212.
Threatened with excommunication by the pope, John was eventually forced to return all the church property and submit to the authority of the pope. Later, In 1215 he was forced by the barons to sign the Magna Carta. His signing of Magna Carta was witnessed by a number of barons including his former ally, William de Warenne, lord of Lewes castle and William de Albini, Earl of Arundel, was one of the twenty-five barons that acted as guarantors of the agreement.