1 King John’s control of the network of royal castles forced the barons opposed to him to remain dispersed in defence of their estates. This allowed John to take the initiative, pressing home the siege of Rochester and then conducting a winter chevauchee the length of England. Other royal captains raided the zone north of London. But John failed to crush the main baronial host, which remained intact in London awaiting the arrival of Prince Louis from France and King Alexander from Scotland with reinforcements.

2 When Louis landed in May 1216, there were mass defections to him, but after failing to bring John to battle, he had to besiege the royal castles holding out in his rear. John’s death removed a major rebel grievance. However, it required William Marshal’s opportunistic victory at Lincoln in May 1217, and the interception of reinforcements from France before Louis gave up. The money spent in the twelfth century on royal castles was amply justified, since their resistance prevented the complete collapse of John’s cause.

The uprising against King John began when rebel barons (mainly from north and east England) seized London in May 1215. John had the great advantage of a network of stone castles across the kingdom. For months he had strengthened them while recruiting knights and crossbowmen from Poitou and hiring mercenaries (routiers) from the Low Countries. His garrisons threatened the estates of rebel barons, forcing them to disperse their forces. But John’s position was flawed. Welsh princes threatened the marches, prince Louis of France and Alexander II of Scotland were poised to invade at opposite ends of the kingdom, and many apparently loyal barons were waiting upon events. The civil war was dominated by local struggles for castles: organized campaigns depended on the availability of a field army, which at first only John possessed.

John invested Rochester in mid-October: its capture would complete the isolation of London and the siege was pressed relentlessly. John’s artillery made little impact, so he undermined the walls, bringing down a tower. The same method gained entry to the keep, but the defenders withdrew behind a cross-wall and held out until their food ran out. A contemporary wrote ‘our age has not known a siege so hard pressed nor so strongly resisted’. The main rebel army could do little to interfere: Louis was slow to send help and John’s captain, Falkes de Breaute, was operating menacingly north of London.

When Rochester fell on 30 November, Alexander II was besieging Norham (19 October-late November 1215), and the northern barons submitted to him. John led a punitive winter campaign against the north before Louis’ arrival. He also needed to plunder rebel estates to reward his routiers. He left St Albans on 19 December and stormed Berwick on 15 January 1216, harrying into Scotland to punish Alexander. By the end of February, he was back at Bedford, having covered over 600 miles (965 km), then spent March mopping up rebel castles in East Anglia. John had taken an impressive list of castles and received the surrender of several rebels. Meanwhile, Falkes and other royal captains had been harrying widely in East Anglia and the east Midlands.

However, the main rebel force remained intact in London, and John had failed to crush the rebellion in the north. Submissions there were temporary – many rebels withdrew into Scotland knowing that John would soon depart. By now, the threat from Louis was growing. John offered easy terms to rebels while gathering his mercenaries in Kent. A storm on 18 May dispersed his fleet, allowing Louis to land. John prepared to fight, but his captains, including the experienced William Marshal, persuaded him not to risk the kingdom in one battle.

As John’s support in the south and east collapsed, he fell back to Corfe. The rebellion revived and many royalists defected, including four earls: two-thirds of the baronage were now in revolt. Louis’ substantial force permitted him to take the offensive in June 1216. He made for Winchester, where he thought John was to be found, seeking a quick victory while John’s cause tottered. The betrayal of Marlborough threatened John’s control of the south-west, and in July he even temporarily lost control of Worcester.

A quick victory eluded Louis, however, and by mid-July he turned on the castles still holding out in his rear. While a force invested Windsor, in early August Louis besieged Dover where Alexander and many northerners joined him. Artillery battered the wall and towers, while miners worked in the ditch under cover of a cat (mobile shelter). The northwest barbican was taken and the gate behind it undermined, but the assault failed. On 14 October, Louis agreed to a truce. The siege allowed John to regain his nerve. In the second week of September he harassed the besiegers of Windsor before drawing them off by a rapid march north, from the Thames at Walton to Cambridge in two days. He relieved Lincoln, and at King’s Lynn arranged the supply of his northern castles. The threat to their estates so alarmed Alexander and the northerners that they quit Dover, dispersing the rebel forces again. John’s death from dysentery at Newark (18 October) ended an effective foray.

John’s death did not cause the rebellion to collapse – the barons swore to continue the war, and Louis captured” Hertford in early December. William Marshal, appointed guardian ‘rector’) of John’s young son Henry III, was unable to take offensive action: the royal treasury was empty, there were disputes among royalist barons, and there was the Welsh threat. Consequently, William secured a truce to last over the winter at the cost of ceding the castles north of London.

The tide began to turn when Louis went to France to raise reinforcements (late February-April 1217). He was briefly trapped in Winchelsea by royalists and guerrillas from the Weald under ‘Willikin of the Weald’. Two leading rebel barons and many lesser ones defected, resenting the favour Louis showed to the French. The guardian William summoned the royalist captains and regained many of the castles lost the previous summer, if only temporarily. The hard core of rebels remained, and when Louis returned in late April with an advance party of 140 knights, he regained Farnham and Winchester.

Louis’ failure to capture Dover now resulted in the division of his forces. He returned to the siege, sending strong forces to relieve Mountsorrel, and then to conclude the siege of Lincoln. This presented William Marshal at Northampton with an” unmissable opportunity. The main royalist forces were already at hand, and if the army which concentrated at Newark (17-18 May) was modest – 406 knights, at least 200 sergeants, and 317 crossbowmen – it had surprise on its side. William approached Lincoln from the north, to maintain the element of surprise and gain the slope. The crossbowmen led the way in order to break up any rebel charge. But the rebels refused battle, wrongly thinking they were outnumbered, and sheltered in the city to continue the siege of the castle and await Louis.

The day was saved by the bishop of Winchester’s reconnaissance. He found a blocked gate in the city walls, which was opened under cover of diversionary attacks on other gates. William burst in, and achieved such surprise that the rebels’ artillery master was killed by men he thought were from his own side. After a stiff fight in the streets of Lincoln itself the rebel army broke. Only three of the heavily armed knights were killed, but the capture of 46 barons and 300 knights tore the heart from the rebellion.

The battle of Lincoln did not end the rebellion however. The royal captains dispersed with their prisoners. Louis, incapable now of taking the initiative, negotiated; But, loyal to his dwindling number of English partisans, he waited upon a final throw: in late August reinforcements sailed from Calais. On 25 August, the fleet was defeated off Sandwich. The guardian, William Marshal, by this time about seventy years of age, was persuaded not to put to sea, but he ensured his cog (ship) was lightly laden, enabling his sergeants to throw potfuls of powdered lime to blind those on the heavily laden French flagship.

Following this disaster, Louis of France sued for peace. What remains particularly striking about this civil war is the way in which both sides generally avoided battle on the grounds that it was far too risky.