Summary The interior of the Centre Bastion of the Indented Lines of the Sheerness defences built in the early-C19 and its associated C19 coastal artillery positions, magazines and early-C20 gun towers, fire control building and pillbox. Reasons for Designation The interior of the early-C19 Centre Bastion of the Sheerness defences with its C19 gun emplacements and magazines and early-C20 gun towers and other structures, is scheduled for the following principal reasons: * Historic interest: as an integral component of the Indented Lines section of the defences of the Royal Naval Dockyard at Sheerness, one on England’s principal naval dockyards. Built to replace the earlier C17 defences, the continual process of adaptation of its armament, and their related structures, in response to improvements in artillery technology, illustrates this particular aspect of our military and defence history. These structures include magazines, artillery positions and the monumental concrete gun towers whose adaptation for naval use during the Second World War adds additional historic interest; * Architectural interest: it provides a well surviving example of the construction and form of C19 and early-C20 artillery positions and magazines; * Rarity: the concrete gun towers are the only known example of this form of artillery structure nationally; * Documentation: the site is well documented including written accounts, historic plans, maps, photographs and surveys; * Potential: for archaeological investigation of the various infilled gun positions. Artefactual evidence relating to the construction and use of the defences may also survive; * Group value: with the other designated buildings and structures associated with Sheerness Dockyard, particularly the other scheduled parts of Sheerness defences. History The Royal Navy dockyard at Sheerness was established in 1665 at the start of the Second Dutch War due to its newly important strategic position, proximity to the anchorage of the Nore and Chatham dockyard and its deep-water channel. Although probably offered some protection by a Henrician fort or blockhouse built at the tip of the Sheerness peninsula in 1545, the new dockyard was burnt during a Dutch raid on the Medway in 1667, shortly after works had begun. As a result of the raid more extensive new fortifications for the dockyard were undertaken by Charles II’s Dutch military engineer, Sir Bernard de Gomme (1620 – 1685). These included a bastioned defensive line, with a ditch and ravelin, cutting across the peninsula to the south of the dockyard, the rebuilding or remodelling of the fort including the curved Half Moon Battery, and indented lines along the eastern (Thames) shore. During the late-C18 a new line of bastioned defences were constructed further to the south, completed by around 1800. These enclosed the area of dockyard workers’ houses called Blue Town and were known as the Sheerness Lines. During the early part of the C19 the naval dockyards at Sheerness were expanded and rebuilt including several new dock basins. This work was largely completed by 1830 and involved the removal of de Gomme’s bastioned line and ditch (replaced with a simple dockyard wall) and the redesign of what were now formally termed the Indented Lines along the Thames shore on a partial bastioned trace. This included the construction between 1828 and 1848 (possibly by 1832) of the Central Bastion, halfway between Bastion 1 at the eastern end of the Sheerness Lines and the fort at the tip of the peninsula. Its role was to provide a concentration of coastal artillery to fire on the navigable passage to the entrance Medway before the guns at Garrison Point would come to bear. The bastion was also frequently used by the Artillery Volunteers, particularly by metropolitan units that had no access to large calibre guns of their own, for practice firing. In 1876 the Centre Bastion was the location for the initial trial of Lieutenant HSS Watkin RA’s Depression Range-finder which was introduced into service in 1881 and provided far more accurate ranging for coastal batteries than previously. The launch of the French ironclad ‘Gloire’ in 1859 and the strengthening of their navy caused an invasion scare and in 1860 the government appointed a Royal Commission to review the defence of the country and, in particular, that of the naval dockyards. As a result Sheerness was provided with a new defensive work known as Garrison Point Fort on the site of de Gomme’s Half Moon Battery and the Queenborough Lines were built around a kilometre south of the Sheerness Lines. In 1845 the Centre Bastion was armed with three 8-inch, 65 cwt smooth-bore muzzle-loading (SBML) guns on the western flank of the bastion, 16 32-pdr, 56 cwt SBML guns on the western salient and four 32-pdr, 56 cwt SBML guns on the eastern salient and flank. These were all on traversing platforms firing through embrasures in the parapet. In 1858 newspapers reported new works to provide 'four extensive magazines and two large buildings with walls of immense thickness to act as a traverse'. Towards the end of the C19 the Sheerness defences were progressively rearmed in line with developments in artillery technology. In April 1871, the armament is given as three 32-pdr guns in the flanks of the bastion, six 9-inch rifled muzzle-loading (RML) guns to each of the salient faces and a 10-inch RML gun on the salient itself. By 1895 the Centre Bastion had two 10-inch rifled breech-loading (RBL) guns in circular open concrete emplacements in the centre of the bastion either side of a magazine (which was adapted from the earlier C19 magazine for the bastion) connected by underground passages with shell hoists at the end, two 7-inch RBL guns firing through embrasures the western flank, and two 64-pdr RML guns in circular emplacements on the eastern flank. There was also a howitzer battery to the west of the 64-pdrs. By around 1900 this armament had been upgraded with two 12-pdr quick-fire (QF) guns, specifically to counter fast torpedo boats, in semi-circular concrete emplacements with underground magazines below, sited on the western salient of the bastion. A searchlight battery replaced the 7-inch RBL guns on the western flank of the battery. The howitzer battery and the 64-pdrs also appear to have been removed but a practice battery of 4.3-pdr QF guns was added in front of the magazine between the 10-inch gun emplacements. On 1 April 1914 the armament of the Centre Bastion is given as the two 12-pdr QF guns but by 1 February 1916, the armament of the bastion consisted of two 4.7-inch Mark IV QF. The circular concrete towers atop which these guns were positioned (the QF guns being more effective when in an elevated position) were probably built, along with a fire-control tower sited to their rear, between 1914 and 1915. The gun towers were linked to the fire-control tower, or Battery Command Post (BCP), by raised walkways. A defensive pillbox was sited to the west of the eastern tower. These were all placed between the two 10-inch RBL gun emplacements and involved the removal of the practice battery. The gun towers resemble C19 Martello towers and it is suggested that this, along with the faux-domestic appearance of the fire-control tower as seen from the sea, was a form of disguise, although if so they were additionally painted with a disruptive camouflage pattern during the First World War. During the Second World War the guns were removed and the towers were modified by the addition of concrete structures on top for use, from 1942, as observation posts by the Royal Navy. The western tower was used by the Extended Defences Officer (XDO) who supervised the firing of the controlled minefield laid at the mouth of the River Medway. Also during the Second World War an octagonal concrete anti-aircraft gun (AA) position was built forward of the western 10-inch RBL gun emplacement. Post-war, between 1947 and 1951, a battery of four guns was sited on the terreplain in front of the First World War pillbox. In February 1958 it was announced that the Royal Dockyard would close and the garrison was decommissioned in 1959. After the dockyard finally closed on 31 March 1960 it was taken over by the Medway Port Authority for commercial use and the defence structures on the bastion either infilled or allowed to decay. Details PRINCIPAL ELEMENTS The most prominent features of the interior of the Centre Bastion are the two early-C20 concrete gun towers, their fire-control tower and defensive pillbox located at the centre of the bastion. They are placed over and adjacent to the C19 magazine for the two 10-inch RBL gun positions. Of the late-C19 gun emplacements themselves, the 10-inch RBL ones have been infilled but probably survive beneath the infill. It is unclear if there is any buried survival of the two 12-pdr QF gun emplacements and their magazines on the western salient. The majority of this emplacement falls within the Centre Bastion section of the Sheerness Defences scheduling (NHLE 1005145). There are also, largely buried, remains of late-C19 batteries at the east end of the bastion. DESCRIPTION The two tapering gun towers are circular in plan, resembling early-C19 Martello towers, and are built of 0.6m thick reinforced concrete with a large central concrete column to take the weight of the gun. The eastern tower (at NGR TQ91380 75332), is built on top of the terreplein of the bastion and was originally around 7m in height. The western tower (at NGR TQ91349 75334) is located at the foot of the ramparts (which are supported here by a curved stretch of concrete revetment) and is consequently taller at around 10.6m. Each originally had a 4.7-inch QF gun in an open emplacement at the top of the tower. Below the parapet at the rear of the towers are a number of square openings which were shell and cartridge lockers, only accessible from an external metal catwalk, now lost. Some of the lockers retain their steel frames. Entrances to the towers are set above ground level on their south-west sides but there is no internal access between floors with the upper level reached via steel catwalks running from the fire control building, now lost. Both towers have additional concrete structures of Second World War date added to the top. That on the western tower was used as an EXDO (Extended Defence Officer) post, controlling the minefields at the entrance to the River Medway. It is a tapering hexagonal structure with a cupola containing an observation slit and probably a chart room, with the crew duty room below. The eastern tower has a flat-roofed concrete observation post, an irregular hexagon in plan, with an entrance on the south side and an oversailing projection above the observation slit on the seaward side. The fire-control tower is also of reinforced concrete, square in plan with a hipped, slate-covered roof and brick chimney on the southern face. High up on the northern face are doorways flanking a pair of window openings with damaged six-over-six timber sash windows, The doorways, which retain their frames, and the western one its door, gave access to the metal catwalks joined to the gun towers. Above this floor is an observation deck with windows whose timber frames survive. The east elevation has three window openings with the remains of timber sashes and a door to the ground-floor room, which has no access to the floors above. The west elevation has doorways at ground (blocked with brickwork) and upper levels and a pair of windows with the remains of timber sashes. The C19 magazine is built under the terreplein and has a stock brick revetment laid in English bond with stone capping, and sloping flank retaining walls topped with stone steps. The centre section of the magazine has two vaulted, brick-lined, casemates, each with a door and window (now partly blocked). Either side of these, and reached by now blocked doors at the side of the central casemates, are pairs of additional vaulted magazines entered via a shifting lobby. Blocked doorways in the flank retaining walls give access to brick-lined vaulted passages connecting with the 10-inch RBL gun positions. The passage on the western side of the magazine terminates at a shell hoist which is still in-situ. The corresponding eastern passage is blocked off beyond the magazines. Sited on the terreplein 10m to the west of the eastern gun tower is a square unreinforced concrete pillbox of early-C20 date. This has loopholes in three sides, that to the north retaining its internal steel shutter, with a doorway in the southern side. The pillbox is adjoined on the east and west sides by low concrete structures, part of the late-C19, 4.3-pdr QF, practice battery which at least partially survives. Buried remains of the octagonal Second World War AA battery to the north-west of the western10-inch RBL gun position are also believed to survive. The two 10-inch RBL gun positions appear to have been infilled around the time the garrison was decommissioned at the start of the 1960s. There is no surface evidence visible but it is likely that the concrete structures survive as buried features. The two 12-pdr QF gun emplacements and their magazines, and a square concrete Controlled Mine Field Post, at the western end of the bastion largely fall within the Sheerness Defences scheduling (NHLE 1005145). These have also been infilled but may survive as buried features. At the eastern end of the bastion the southern of the two late-C19 64-pdr RML gun emplacements and the battery direction finder are believed to survive, although heavily overgrown, and the northern emplacement may also survive as buried remains. A cartridge store at the south-east corner of the bastion survives without its eastern end. EXCLUSIONS The following are excluded from the scheduling: all modern railings, fences or fence posts; lights and lamp posts; telegraph poles and drains and drain covers. However, the ground beneath all these features is included.