In 1215 King John had agreed to the terms of Magna Carta, but he then reneged on his word immediately, plunging the kingdom into war. The rebellious barons, seeing no other option but to overthrow John, offered the English throne to Louis, the eldest son and heir of the French king. Louis arrived in May 1216 with an army at his back, and by the autumn of that year he had around half of England’s geographical area under his control, while some two-thirds of its nobles had sword allegiance to him. However, the choice of a French prince as replacement monarch had enormous repercussions and meant that the conflict took on a new characteristic: it was now not merely the case of a king and his supporters fighting off an internal rebellion, but rather a war in which the defenders were battling to prevent a foreign takeover.
