A large number of barons, led by Stephen Langton the Archbishop of Canterbury, meet King John on an island in the Thames at Runnymede. They forced the king to sign the 'Great Charter' or Magna Carta that would limit the power of the monarchy. The barons insisted that the old feudal contract should be reinstated and that the king should abide by the laws that the rest of the population did. The feudal contract allowed the barons to run their own lands, renting it from the king but paying rent by supplying knights rather than money. This feudal system had been set up by William the Conqueror. ^[1]

Pope Innocent III annulled the Magna Carta freeing King John from its limitations. The Pope annulled the charter on the grounds that the King only signed it because he was forced to and that the document was illegal. The Pope was prepared to support John against the rebel barons because he wanted him to take a key role in a new crusade.

After the Magna Carta was annulled and it was clear that King John was not going to agree to the terms of the charter the civil war between King John and the rebel barons began.The barons offered the English crown to Prince Louis, the son of King Philippe II of France and invited him to invade England. John confiscated the rebel barons' lands and gave them to his own supporters. King John besieged Rochester Castle where a garrison of men had been left by the barons. The garrison was starved out and the castle fell to the King.

The Magna Carta was revised at King Henry's Council at Bristol.

With the introduction of Peter de Roches as justiciar and the removal of Hubert de Burgh, control of the Exchequer came under Poitevin control and possibly reversed the gains created by the Magna Carta in 1215. King Henry III was given control of central administration. This angered the Barons and a group led by Richard Marshall, Earl of Pembroke opposed the changes. ^[2]