King John undertook some building works at Windsor, but primarily to the accommodation rather than the defences. The castle played a role during the revolt of the English barons: the castle was besieged in 1214, and John used the castle as his base during the negotiations before the signing of the Magna Carta at nearby Runnymede in 1215. In 1216 the castle was besieged again by baronial and French troops under the command of the Count of Nevers, but John's constable, Engelard de Cigogné, successfully defended it.