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. 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, which changed the face of the war once again, for now the English king trying to fight off an invader was not a hated tyrant but an innocent child. Henry’s supporters were thus able to position themselves as acting in defence of the realm, able to appeal to a nascent sense of national identity.
Louis’s forces comprised a combination of rebellious English barons plus those French nobles who had accompanied him. However, he did not have the full backing of his father, King Philip II Augustus of France, and his army was therefore not as large as it needed to be if it were to overrun England completely. Throughout the summer and early autumn of 1216 he personally supervised the siege of the great fortress of Dover, ‘the key to England’, but withstood, meaning that Louis lost his campaign momentum and the English royalist party was able to regroup.
Louis began another siege of Dover in the spring of 1217, and was obliged to remain there along with around one third of his army, while a second part made its way north to Lincoln. There the French and rebel forces succeeded in taking the city but not the castle, which held out against them under the command of the castellan, Dame Nicola de la Haye. William Marshal knew that 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 took place in the streets of the city on 20 May 1217, and was a resounding victory for the royalists.
Many of the French and rebel barons had been captured, leaving Louis with insufficient numbers of men, so he appealed to France, where his wife (the redoubtable Blanche of Castile) raised an army of reinforcements that set sail in August.
A storm meant that the fleet took much longer to cross the Channel than expected, and the additional time gave Marshal the opportunity to muster his forces on the south coast. In what was an extremely unusual manoeuvre at the time, rather than waiting for the French forces to land, the English royalist army embarked on ships to intercept them. The Battle of Sandwich took place at sea on 24 August and was, a resounding win for the royalists.
With only a very small army left to him, and no further hope of reinforcements, Louis was obliged to come to terms, and he relinquished his claim to the English throne. He sailed away in September 1217, never to return, leaving England to Henry III.
Louis later acceded, as expected, to the French throne. If his campaign in England had been successful then that kingdom might have been subsumed into France, or at the very least been ruled in perpetuity 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.
