King John was forced to sign the Magna Carta in June of 1215 by the Barons, who had taken over London and nearly captured the king at Windsor in retaliation for the heavy taxes imposed on them. Even after signing the final version of the document that would become the Magna Carta at Runnymede, King John had no intention of adhering to the agreement, which led to the Baron's War.
The king imposed the exorbitant taxes on the Barons and the English people to pay to Pope Innocent III as recompense for retaliating against the Pope's choice for archbishop of Canterbury and to fund expeditions to attempt to regain the lost territories of Aquitaine, Poitou and Anjou. The Barons did not agree with the ruthless way that the king ruled. In an attempt to bring the king under control, the Barons drew up a list of their demands known as the Articles of the Barons in January of 1215. The Barons then began to fight the king with physical force, capturing London in May and forcing the king to agree to the meeting at Runnymede in June. Once the Magna Carta was signed, the Barons renewed the Oath of Fealty to the king. Copies of the Magna Carta were distributed to bishops, sheriffs and other nobles in England.