Behind the dam was an artificial lake along the south and west sides of the castle, protecting it from a land approach.

The feudal summons for the siege was pushed back from December 1265, finally occurring on 21 June the next year.

[4] Outside of the castle was the feudal host of England as summoned by Henry III, along with his sons, the Lord Edward and Edmund, who had been attempting to contain the garrison since the prior autumn.

Numerous stone-throwing devices, presumably trebuchets, were brought to the siege, as well as "turres ligneas", or wooden towers.

[9] Time, however, was the only weapon left at their disposal, and the patient waiting finally paid off; with the garrison running out of food and suffering from disease, they finally surrendered on 13 December 1266[10] and accepted the terms of the Dictum of Kenilworth, which later became part of the Statute of Marlborough, four chapters of which are still in force in English law.