 After the Crimean War broke out in 1853 , fresh concerns of invasion were raised and the coastline was refortified . The castle was redeveloped as part of this work in 1855 , and two new gun positions built around the old blockhouse . In 1887 , the castle was equipped with 64 @-@ pound ( 29 kg ) rifled , muzzle @-@ loading artillery pieces , supported by volunteer forces and used for training purposes , but the weaponry became obsolete and the site had fallen out of use again by the end of the century . 
