 Rochester 's constable in 1264 , Roger de Leybourne , held the castle in support of Henry . John de Warenne , Earl of Surrey , was the garrison 's co @-@ commander . A baronial army led by Gilbert de Clare , Earl of Hertford , laid siege to the castle on 17 April that year . Having marched from the earl 's castle to Tonbridge the army attacked from the Rochester side of the river , either the south or west . While the army advanced towards the city the royalist garrison set alight the suburbs . The king 's hall within the castle was also burned down , although it is unclear why . An army under Simon de Montfort marched from London with the intention of attacking the city from another direction . The earl 's first two attempts to cross the Medway were fought back , but he was successful on 18 April , Good Friday . The method used is uncertain , although it involved a fire @-@ ship . The smoke may have been used as cover for the rebels , or the ship may have been used to burn the bridge while the army travelled by water . In a co @-@ ordinated attack that had been pre @-@ arranged , the armies of de Montfort and de Clare attacked the city . They entered Rochester in the evening and that night the cathedral was raided . The following day the rebels captured the castle 's outer enclosure and the royal garrison retreated to the keep . Because the next day was Easter Sunday there was no fighting , though hostilities resumed on the Monday . Siege engines were set up and targeted the keep . As in 1215 the keep proved resistant to missiles , and after a week had not succumbed . According to one contemporary source , the besiegers were about to dig a mine beneath the tower , but the siege was abandoned on 26 April when the earls received news of a relief force led by Henry III and his son , Prince Edward . 
