. ▁Ro chester ▁bridge ▁was ▁pulled ▁down ▁to ▁prevent ▁the ▁arrival ▁of ▁a ▁relief ▁force ▁from ▁London . ▁The ▁sie ge ▁that ▁followed ▁was ▁the ▁largest ▁in ▁England ▁up ▁to ▁that ▁point , ▁and ▁would ▁take ▁nearly ▁two ▁months . ▁ ▁B ole y ▁Hill ▁to ▁the ▁south ▁of ▁the ▁castle ▁may ▁have ▁been ▁used ▁as ▁John ' s ▁headquarters ▁during ▁the ▁sie ge . ▁According ▁to ▁the ▁Bar n well ▁chron ic ler , ▁five ▁sie ge ▁engines ▁hur led ▁a ▁bar rage ▁of ▁stones ▁at ▁the ▁castle ' s ▁wall ▁day ▁and ▁night . ▁These ▁were ▁supported ▁by ▁miss iles ▁from ▁smaller ▁b ows ▁and ▁cross b ows . ▁The ▁Bar n well ▁chron ic ler ▁claimed ▁they ▁sm ashed ▁a ▁hole ▁in ▁the ▁castle ' s ▁outer ▁walls ; ▁Roger ▁of ▁Wend over ▁assert ed ▁they ▁were ▁in effect ive ▁and ▁that ▁John ▁turned ▁to ▁other ▁methods ▁to ▁bre ach ▁the ▁def ences . ▁A ▁letter ▁dated ▁ 1 4 ▁October ▁indicates ▁John ▁was ▁prepar ing ▁to ▁und erm ine ▁the ▁castle ' s ▁walls . ▁He ▁wrote ▁to ▁Can ter bury , ▁asking ▁for ▁the ▁production ▁" by ▁day ▁and ▁night ▁of ▁as ▁many ▁pick s ▁as ▁you ▁are ▁able " ▁and ▁that ▁they ▁be ▁sent ▁to ▁Ro chester . ▁On ▁ 2 6 ▁October ▁a ▁relief ▁force ▁of ▁ 7 0 0   hor se ▁was ▁sent ▁from ▁London . ▁They ▁turned ▁back ▁before ▁arriv ing , ▁perhaps ▁because ▁they ▁heard ▁the ▁king ▁was ▁adv ancing ▁to ▁meet