main guard room. Between 1860 and 1874 outworks were added. By now, within the ramparts, the Citadel contained barracks, stores and magazines arrayed around a large parade ground. The bomb-proof Officers' Quarters and Mess, built by Major William Jervois in 1860, was designed in part to be able to function as a defensible keep in the event of the Citadel being stormed by the enemy. After 1890 the Citadel ceased to have a defensive role and functioned instead as a large barracks and mobilisation centre, with additional hut accommodation provided for up to 900 soldiers in total. During World War I it was occupied by 3rd (Reserve) Battalion, Buffs (East Kent Regiment) charged with training reinforcement drafts for the service battalions serving overseas. In 1956 the Citadel was handed over to HM Prison Service; it served successively as a Borstal, a Youth Custody Centre and a Young Offender Institution. The Armaments It was initially envisaged that the Citadel would be armed with forty-three 18-pounder guns, and thirty-one carronades. By the 1860s it had been re-armed with eighteen 18-pounder carronades, twenty 12-pounder carronades and ten 8-inch mortars. Drop Redoubt The Drop Redoubt is one of the two forts on Western Heights, and is linked to the other, the Citadel, by a series of dry moats (the lines). It is, arguably, the most impressive and immediately noticeable feature on Dover's Western Heights. Prior to construction of the Redoubt a bastioned fort had stood there as part of the 18th-century fortifications. The construction of the Redoubt was in two periods: the first being from 1804 to 1808 during the Napoleonic Wars, and the second from 1859 to 1864 following the recommendations of the 1859 Royal Commission. First Period The original form of the Drop Redoubt was a simple pentagon, formed by cutting trenches into the hillside and revetting (facing) them with brickwork. Thus, the Redoubt was a solid ‘island’ with barracks, magazine, and artillery, on top. Originally, it would have accommodated 200 troops but, by 1893, the numbers had been reduced to just 90. A striking feature of the first period is the Soldiers’ Quarters – five bomb-proof casemates. These are parabolic in cross section and covered in a thick layer of earth to withstand the effect of mortar-bombs. The windows at the rear of each open into a trench, to protect them against blast. Second Period The rise of Napoleon III during