In 1199, Richard died and John became king. War with France was renewed, triggered by John's second marriage. While asked to mediate between the rival families of Lusignan and Angoulâme, he married the Angoulâme heiress Isabella, who had been betrothed to Hugh de Lusignan. A rebellion broke out and John was ordered to appear before his overlord, Philip II of France. His failure to do so resulted in war.
By 1206, John had lost Normandy, Anjou, Maine and parts of Poitou. These failures were a damaging blow to his prestige and he was determined to win them back. This required money, so his government became increasingly ruthless and efficient in its financial administration. Taxes soared and he began to exploit his feudal rights ever more harshly.
This bred increasing baronial discontent. Negotiations between John and his barons failed and civil war broke out in May 1215. When the rebels seized London, John was compelled to negotiate further and, on 19 June at Runnymede on the River Thames, he accepted the baronial terms embodied in the Magna Carta, which limited royal power, ensured feudal rights and restated English law. It was the first formal document stating that the monarch was as much under the rule of law as his people, and that the rights of individuals were to be upheld even against the wishes of the sovereign.
This settlement was soon rendered impractical when John claimed it was signed under duress. Pope Innocent took his side and in the ensuing civil war John laid waste to the northern counties and the Scottish border. Prince Louis of France then invaded at the barons' request. John continued to wage war vigorously, but his death in October 1216 enabled a compromise peace and the succession of his son Henry III.