With the war being lost after the loss of Northampton, Montfort knew he needed to draw the king’s forces south if he hoped to regain the initiative. Now that Gilbert de Clare was finally on board, he worked out a plan for Clare to strike the royalist stronghold of Rochester from the south while he advanced on it from the west. This way he could also remove the rowdy elements from London that had been close to sacking the city from within. On Good Friday, 18 April 1264, Simon breached the city’s defenses by use of a fireboat alight with pitch, coal and fatty pork, a tactic he may have learned of on the continent. His irregulars swarmed in and took the place apart much the way Henry and Edward’s men were doing in the Midlands at that point. They ransacked the church of St. Andrew, stole its treasure, and stabled their horses inside. The siege of the castle commenced, with a break for Easter Sunday, but the Montfortians were unable to take the great Keep manned by Warenne and Leybourne. By April 26 Simon had to call of the siege when Henry and Edward arrived in the southern theatre to relieve the city. Far from a defeat, Montfort had achieved his objective: he now had Henry where he could strike at him.