quality:correction
Decline and the loss of Anjou

Richard's failure to provide an heir caused a succession crisis and conflict between supporters of the claim of his nephew, Arthur, and John. Guillaume des Roches led the magnates of Anjou, Maine, and Touraine declaring for Arthur. Once again Philip II of France attempted to disturb the Plantagenet territories on the European mainland by supporting his vassal Arthur's claim to the English crown. John won a significant victory while preventing Arthur's forces from capturing his mother, seizing the entire rebel leadership at the Battle of Mirebeau and his sister Eleanor, Fair Maid of Brittany.

John disregarded his allies' opinions on the fate of the prisoners, many of them their neighbours and kinsmen. Instead he kept his prisoners so vilely and in such evil distress that it seemed shameful and ugly to all those who were with him and who saw this cruelty, according to the Histoire de Guillaume le Maréchal. As a result of John's behaviour the powerful Thouars, Lusignan, and des Roches families rebelled and John lost control of Anjou, Maine, Touraine, and northern Poitou. His son, King Henry III, maintained the claim to the Angevin territories until December 1259 when he formally surrendered them and in return was granted Gascony as duke of Aquitaine and a vassal of the king of France.

John's reputation was further damaged by the rumour, described in the Margam annals, that while drunk he himself had murdered Arthur, and if not true it is almost certain John ordered the killing. There are two contrasting schools of thought explaining the sudden collapse of John's position. Sir James Holt suggests this was the inevitable result of superior French resources. John Gillingham identifies diplomatic and military mismanagement and points out that Richard managed to hold the Angevin territory with comparable finances. Nick Barratt has calculated that Angevin resources available for use in the war were 22 per cent less than those of Philip, putting the Angevins at a disadvantage.

By 1214, John had re-established his authority in England and planned what Gillingham has called a grand strategy to recapture Normandy and Anjou. The plan was that John would draw the French from Paris, while another army, under his nephew Otto IV, the Holy Roman Emperor, and his half-brother William attacked from the north. He also brought his niece Eleanor of Brittany, aiming to establish her as Duchess of Brittany. The plan failed when John's allies were defeated at the Battle of Bouvines. Otto retreated and was soon overthrown, William was captured by the French and John agreed to a five-year truce.

From then on John also gave up the claim to Brittany of Eleanor and had her confined for life. John's defeat weakened his authority in England, and his barons forced him to agree to Magna Carta in 1215, which limited royal power. Both sides failed to abide by the terms of Magna Carta, leading to the First Barons' War, in which rebellious barons invited Prince Louis, the husband of Blanche, Henry II's granddaughter, to invade England. Louis did so but in October 1216, before the conflict was conclusively ended, John died. The official website of the British Monarchy presents John's death as the end of the Angevin dynasty and the beginning of the Plantagenet dynasty.