Medieval monks portrayed King John as an evil monster. Modern historians portray him as an energetic king who tried to increase his power in difficult circumstances.
John's brother, Richard I, had spent all the money in the treasury on his Crusades. The Crusades were a series of military campaigns over hundreds of years to take sole control of Jerusalem for the Christian faith. Richard also let the barons become too powerful whilst he was in the Holy Land.
John collected taxes, modernised the government and exerted his power over the Church, Scotland and Ireland. This made him unpopular with the barons. In 1201-2, helped by King Philip of France, the lords of Lusignan, a powerful alliance of French nobles, rebelled against John. John mounted a huge campaign to re-conquer Normandy, but was badly defeated at the Battle of Bouvines (1214). John was forced to pay the huge sum of 20,000 marks and concede some lands in France in order for King Philip to recognise him as the heir to Richard I. John was exposed as diplomatically weak.
The reign of King John shows what often happened in the Middle Ages when a monarch lost a war – his authority was completely undermined. The barons rebelled and, on 15 June 1215, they forced John to agree to Magna Carta (The Great Charter) - a set of demands by which the barons tried to limit the power of the king to their advantage.
The reign of King John was a turning point in the history of England's government. The barons – successfully – had said 'no' to the king, and made him do as they wanted. The charter only spoke about freemen and not the majority of people who were peasants. No monarch of England ever had unrestricted, or 'absolute', power again and within a century England saw the beginnings of Parliament.