1217

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 sworn allegiance to him. However, the choice of a French prince as replacement monarch had enormous repercussions. The conflict took on a new characteristic: it was no longer merely a king and his supporters fighting off an internal rebellion, but a war to prevent a foreign takeover.

John’s death in October 1216 left his family’s claim to the throne in the hands of his 9-year-old son, Henry, and a group of loyal nobles headed by his regent, William Marshal. This changed the face of the war, as the English king trying to fend off an invader was now an innocent child rather than a hated tyrant. Henry’s supporters were thus able to position themselves as defenders of the realm, appealing to a nascent sense of national identity.

Louis's forces, comprising rebellious English barons and those French nobles who accompanied him, did not receive full backing from his father, King Philip II Augustus of France. Therefore, his army was not as large as needed to overrun England completely. During the summer and early autumn of 1216, he personally supervised the siege of the great fortress of Dover, ‘the key to England’. The fortress withstood, causing Louis to lose momentum and allowing the English royalist party to regroup.

In spring 1217, Louis began another siege of Dover, forced to remain with one-third of his army, while another part advanced north to Lincoln. The French and rebel forces succeeded in taking the city but not the castle, which held out under the command of the castellan, Dame Nicola de la Haye. William Marshal knew it would be disastrous for Henry’s campaign if the castle were to fall, so he summoned all those remaining loyal, and they marched.

The Battle of Lincoln, taking place in the streets of the city on 20 May 1217, was a resounding victory for the royalists. Many of the French and rebel barons were captured, leaving Louis with insufficient numbers. He appealed to France, where his wife, the redoubtable Blanche of Castile, raised an army of reinforcements that set sail in August.

A storm delayed the fleet's crossing of the Channel, providing Marshal with time to muster his forces on the south coast. Rather than waiting for the French forces to land, the English royalist army embarked on ships to intercept them. The Battle of Sandwich occurred at sea on 24 August and was another resounding win for the royalists.

With only a very small army left and no further hope of reinforcements, Louis was obliged to come to terms and relinquished his claim to the English throne, sailing away in September 1217, never to return. This left England to Henry III. Later acceding to the French throne, had Louis's campaign in England been successful, the kingdom might have been subsumed into France or ruled perpetually by a Capetian rather than a Plantagenet. The two-part siege of Dover and the battles of Lincoln and Sandwich had, in a very real sense, saved England.

1217 by Dr Catherine Hanley offers a detailed narrative of these tumultuous events that shaped English history.