The barons, meanwhile, had been making slow progress with their siege of Northampton Castle. Not having any siege engines, they would probably have conceded, put them at a distinct disadvantage. Several of their number had already been killed, including Robert fitz Walter’s standard-bearer, who had been shot in the head by a crossbow bolt. After a week or so, having achieved nothing, they moved twenty miles east to Bedford and took the castle there without a fight, thanks to the defection of its keeper, William de Beaumont. But this was only a minor victory, for Bedford was a far less important fortress than Northampton. Their threat to humble the king by seizing his castles was not off to an auspicious start.
It was at this point that the rebels received exciting intelligence. A faction of Londoners was ready to help them, provided they moved fast. Bedford is almost sixty miles from the capital, but by setting off at once the barons managed to cover more than half that distance, arriving at Ware in Hertfordshire later that same day. They then, according to Roger of Wendover, rode through the night to reach London early in the morning on 17 May. It was a Sunday, and so they waited for the moment when most of the citizens were attending Mass. At that hour their accomplices within the city helped a small number of rebels to scale the walls, and they in turn were able to open the gates and admit those waiting outside. In this way London was taken by stealth. The barons quickly captured almost all the king’s supporters and plundered their possessions; under fitz Walter’s direction, the houses of the Jews were destroyed and their stones used to strengthen the city walls. Only the Tower and its small royalist garrison held out. But having manned the walls and stationed their own sentries on the gates, the barons were able to settle down to build siege engines.
The fall of London was the tipping point. For John, it meant not only the ignominy and embarrassment of having lost his capital; far more damaging, it also meant the loss of his main treasury at Westminster, which must now have fallen into the hands of his enemies. Although some treasure was shut up in the Tower, this was small consolation since the king himself could no longer get to it. John was forced to turn to the regional treasuries that Peter des Roches had created in 1209, but these had been much depleted by the failed campaign of 1214. Nor could they be easily replenished, for the loss of London also meant the loss of the Exchequer and all its records. Regular royal finance collapsed, and the king was driven to the desperate expedient of pawning his prized collection of jewels. For a man who was reliant on mercenaries, this was a catastrophe.
Perhaps even more important than all of this, the fall of London gave heart to the rebels. At a stroke they had gone from holding a single royal castle of little significance to controlling the principal city in the kingdom. According to Wendover, they now sent letters to all the other magnates, urging them ‘to abandon a king who was perjured and warred against his own barons’, at the same time threatening to regard all who did not join them as their enemies. Previously, says the Crowland chronicler, the rebels had mostly been young men, eager to make a name for themselves in war. But now fathers began to join sons, and uncles to join nephews; at this juncture, if not before, the earls of Hertford and Norfolk followed their heirs into rebellion. Such was the scale of the swing, in fact, that the chroniclers found it easier to list those who had not abandoned John’s cause. William Marshal, Ranulf of Chester and William Longsword, the king’s half-brother, are named among the remaining loyalists, along with the earls of Surrey, Derby and Arundel. Apart from them and a handful of lesser barons, said Ralph of Coggeshall, everyone else had gone over to the rebels. New risings broke out across the country. In the north a rebel army occupied Lincoln and laid siege to its royal castle. In Devon rebels who had recently been dispersed by John’s Flemish mercenaries renewed their attacks and ravaged the king’s manors. Shropshire was invaded by Llywelyn and the Welsh, and the king of Scots was also said to be in league with the barons. Even Philip Augustus had pledged his support and promised to send as much aid as he could supply.
A week after London’s fall, John accepted that he had no choice but to negotiate...
