How did Magna Carta come about?
King John became King of England, Duke of Normandy (in France), Duke of Aquitaine (in France), Count of Anjou (in France), and Lord of Ireland in 1199. John inherited England, and of most of western France, where he was more powerful than the King of France.
In 1204, the King of France took Normandy and Anjou from John. John wanted to regain his lost territories in France, which his family had ruled for hundreds of years. John's attempts to recapture his family's lost territory in France, meant that he needed money. He raised taxes in England much higher than they had been before, causing officials to become more and more oppressive in the way they collected these taxes.
Raising taxes made John increasingly unpopular with the English barons, whom the king relied on to assist him in governing the kingdom. The immediate cause of the Barons' rebellion was the decisive defeat in battle of King John's army at Bouvines in 1214, by the force of the king of France. This, together with John's personality and ruthless actions, which seem to have provoked hostility and fear in others more than the loyalty on which kings of this period had to rely, caused much opposition among the barons. The defeat at Bouvines led to the meeting at Runnymede, but opposition to the king had been brewing for longer; in 1212 there had been rumours of a plot to murder him.
Magna Carta was hammered out in negotiations between the leaders of two armed parties – the king on one side and the rebel barons on the other. Neither side expected it to settle the matter, and both anticipated continued war between king and barons. Within three months of it being issued at Runnymede, Pope Innocent III had annulled the charter, the rebels had renounced their homage to the king and invited the son of the king of France to take the crown of England in John's place.