In 1213 King John signed the Concessions to the Pope agreeing to pay tribute to the Roman Cult. In 1215 the Welsh Barons rose up in rebellion because of the revenue generation activities and the Magna Carta resulted when they put a sword to King John's throat and demanded that he sign it. Because the Crown was unable to pay the tribute, they were seized by the Roman Cult. The video below goes into it in more detail.