Fort Monckton


Heritage Category:
Scheduled Monument
List Entry Number:
Date first listed:
Date of most recent amendment:
Statutory Address:
Military Road, Alverstoke, Gosport, Hampshire, PO12 2AT


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Statutory Address:
Military Road, Alverstoke, Gosport, Hampshire, PO12 2AT

The building or site itself may lie within the boundary of more than one authority.

Gosport (District Authority)
Non Civil Parish
National Grid Reference:


The upstanding remains, earthworks and buried remains of a late-C18 bastioned artillery fort.

Reasons for Designation

Fort Monckton, a bastioned artillery fort built between 1781 and 1790 to defend the western approaches to Portsmouth Harbour, is scheduled for the following principal reasons: * Rarity: as a rare surviving true bastioned artillery fort of which there are just eight examples in England; * Archaeological importance: as an artillery fort at the forefront of late C18 British military architecture, incorporating advanced features such as casemates and a unique form of caponier; * Historic importance: as a fort built following invasion concerns in the late C18, which continued to form a major part of Portsmouth’s defences in the earlier C19 before being used as a base for experimental development of sea mines and electric lighting; * Architectural importance: as a finely constructed and carefully detailed late C18 artillery fort with bastions, curtain walls and buildings erected in high quality tooled Purbeck ashlar masonry; * Survival: most of the original built fabric and features survive, as well as substantial remains of the earthworks of the outer works; * Vulnerability: an artillery fort’s outer works are particularly vulnerable to damage by later activity but these earthworks survive reasonably well, especially the low slopes of the glacis which are unusually well preserved; * Documentation: the site is well documented in both historical and archaeological terms, including written accounts, historic plans, maps and photographs, as well as recent topographical and LiDAR surveys; * Potential: for archaeological deposits associated with the construction and use of the fort, which with the built fabric will significantly enhance our understanding of C18 bastioned forts. In addition, buried remains or artefactual evidence relating to the C16 Hasleworth Castle may also survive; * Diversity: the artillery fort contains a high diversity of surviving features including the outer works, glacis, redan, curtain walls, bastions, ravelin, covered way, dry ditch, caponiers, guardhouse, casemates, barrack block, main magazine and officers’ quarters; * Group value: with the designated artillery fortifications associated with Portsmouth Harbour, such as the contemporary Fort Cumberland, as well as Fort Gilkicker, Fort Blockhouses, Fort Grange, Southsea Castle, Portsmouth town defences and Eastney Fort, among many others; together forming an impressive ensemble that illustrates the defence of this strategic harbour over a long period of time.


Fort Monckton is a bastioned artillery fort built between 1781 and 1790 to defend the western approaches to Portsmouth Harbour. It is positioned on the shoreline north-east of Gilkicker Point, which was close to the mouth of the River Alver in the late C18 (the river formerly entered the sea immediately to the west of the fort). Fort Cumberland, a contemporary artillery fort at the mouth of the Langstone Channel, defended the eastern approaches to Portsmouth Harbour and survives in the care of English Heritage.

The site of Fort Monckton has been fortified over a long period. In the mid-C16 Haselworth Castle, a Henrician artillery castle, was built in this position to defend Portsmouth Harbour. It is shown on the Cowdray Engraving, which depicts the sinking of the Mary Rose in 1545, and was probably of similar form to the extant artillery castles at Calshot (1539-40) and Pendennis (1540-45). The castle fell into a state of decay by the late C16 and its exact position is not known, although cartographic evidence indicates that it was probably on the site of Fort Monckton.

The planning and construction of Fort Monckton took place during the wars of the late C18, a period of concern about threats to naval facilities and possible large-scale invasion. The need for improved defences in the area was influenced by contemporary military events including attacks on the Channel Islands, The American War of Independence and an aborted attack on Plymouth by a combined French and Spanish fleet. Military commanders placed emphasis on the outer defences to the east and west of Portsmouth Harbour, notably in the Stokes Bay and Langstone Harbour areas, reflecting both the increased range of artillery and information provided by captured French spies. A new defensive work was built at the Fort Monckton site in c1779 by Lieutenant Colonel John Archer, under the command of the Governor of Portsmouth, Lieutenant General Robert Monckton. This was probably a temporary earthwork structure with three bastions and a magazine which was completed by 1782. Initial plans for a permanent fort were made at the same time but were improved by the Duke of Richmond in 1783, the newly-appointed Master General of the Ordnance, who also obtained political support for its construction. The permanent fort was built on the same site from 1781 and was completed in 1789-90, replacing the temporary fort; it was named after Monckton following his death in 1782. As constructed, the fort was to accommodate 14 officers, two staff sergeants and 298 rank and file.

The design of Fort Monckton combined established features of a bastioned fortress, as they had developed up to the late C18, with advanced features reflecting new concepts in military planning and the particular requirements of the site. It was constructed to defend the main approach to Portsmouth Harbour from the west, with a main battery of 22 casemated guns facing The Solent. Casemates were an advanced feature that became more common in mid-C19 defences. A single-storey barracks block was built above the casemates; a pair of octagonal cookhouses were built to the rear of each end of the barracks block but do not survive. The main ramparts were built to a roughly triangular plan with bastions at the main apexes flanking curtain walls. An additional pair of bastions flanked the seaward-facing battery. All five bastions and the landward-facing ramparts had top-mounted guns in embrasures, a more typical 18th century arrangement. The ramparts and bastions were enclosed by a dry ditch. Another advanced feature was the use of two caponiers (blockhouses containing gun ports), projecting into the ditch behind the bastions flanking the seaward-facing battery. The caponiers were strongly built in brick to a distinctive arrow-head plan and provided additional cover for the ends of the ditch, which were open to the beach. The main entrance to the fort was a gatehouse in the centre of the north-facing curtain wall, flanked by the embrasures of the projecting bastions. The main magazine was built as a brick barrel-vaulted building towards the centre of the fort.

The fort was surrounded by an extensive system of defensive earthworks, originally more than double the area of the fort itself. The ditch was enclosed by a covered way (a forward infantry position on the outer edge of the ditch) and a glacis (low artificial slopes surrounding the fort). The covered way was notably wider than that at Fort Cumberland, probably because Fort Monckton’s position meant it had to defend a larger adjoining area. It included two triangular ravelins (bastion-shaped outer works) projecting into the glacis. There were ten traverses along the course of the covered way; low-walled embankments intended to prevent flanking fire, one of which survives. The road entering the fort from the north was defended by a detached triangular earthwork, referred to as redan or redoubt in contemporary plans. The road originally crossed the ditch on a drawbridge, which has been replaced by a short causeway. The earthworks included water defences which were adapted from natural features. A lake in the course of the River Alver was adapted to form the western limit of the glacis. A sluice was added to its south end to enable defensive flooding of the area behind Stokes Bay beach. A narrow channel or wet moat extended eastwards from the north end of the lake to form the northern edge of the glacis.

In 1805 Fort Monckton held a substantial armament of twenty-four 36-pounder guns, twenty-three 18-pounder guns and twelve 12-pounder guns. During the first half of the C19 the barracks above the main battery were extended at both ends to provide officer’s quarters. A sea wall was built extending from the fort along the beach towards Haslar which included a redoubt at its north-west end, parts of which survive. By the 1850s the western defences of Portsmouth Harbour were recognised as deficient, which led to the construction of an auxiliary battery to Fort Monckton at Gilkicker Point, first shown on the site plan of 1858. This was rebuilt as Fort Gilkicker in the 1860s; a modern casemated battery which was better placed to defend The Solent, partly replacing the defensive role of Fort Monckton.

The construction of improved outer defences for Portsmouth and Gosport in the 1860s, including Fort Gilkicker and the Stokes Bay Lines, saw Fort Monckton being used mainly as barracks and workshops in support of the new defences. It was occupied by the Royal Engineers from 1878, leading to the conversion of casemates into workshops and stores and the former central magazine into a canteen. The Royal Engineers used the site for the development of sea mines and electric searchlights, in conjunction with new facilities built in Stokes Bay. The number of guns at Fort Monckton was greatly reduced in the 1880s, and limited to obsolete smooth-bore types, at which time many of the disused embrasures were blocked.

In the early C20 the fort continued to fulfil an ancillary role; it was armed with six machine guns on infantry or parapet carriages in 1902. During the First World War it was used to mount anti-aircraft searchlights. Three heavy anti-aircraft (AA) guns were mounted on the south-west and north-east batteries during the Second World War when the fort housed the Gun Operations Room for Gosport AA defence. Between 1939 and 1956 a twin six pounder gun was also mounted at the fort for coastal defence. More extensive additions were made in the late C20. The south extension of the barracks block was rebuilt in the 1970s, followed by the addition of large accommodation buildings on the former terreplein (the level surface on top of the rampart) behind the west curtain wall. More recent additional buildings have been added to the north of the barracks block, in the ditch, and outside the northern perimeter of the fort. It remains in MOD use with no permitted public access.


PRINCIPAL FEATURES Fort Monckton is situated on the shoreline north-east of Gilkicker Point at Gosport. It originally defended the western approaches to Portsmouth Harbour. The ramparts forming the main enclosure or enceinte are built to a broadly triangular plan with three bastions at the main apexes flanking curtain walls, as well as an additional pair of bastions flanking a seaward-facing casemated battery. A dry ditch surrounds the ramparts into which projects two caponiers to defend the ends of the ditch (now blocked) where it originally met the beach. Beyond the ditch is a covered way conforming to the plan of the internal ramparts except for two triangular ravelins, which project outwards to cover the sloping ground or glacis beyond it. This, in turn, is surrounded by the earthwork remains of a partly-infilled wet moat at the north and an artificially-shaped defensive lake at the west.

DESCRIPTION The main approach to the fort is at the north-east via Military Road. It was originally protected by a detached triangular enclosure, known as a REDAN or redoubt. This survives as a bank up to c1.5m high, which has been denuded and truncated by the current roadway and golf course. The approach road passes through the redan and then crosses the earthworks of the outer moat and takes a curvilinear course, diverging from the original route, before bisecting the earthworks of a ravelin, passing through the covered way and to the guardhouse. Although the current road diverges from the original route, there is a surviving length of the chicane immediately east of the ravelin; it is a sinuous sunken roadway with brick walls c1m high. In front of the guardhouse was originally a timber bridge, which incorporated a draw bridge and spanned the dry ditch of the fort but it has been replaced by a causeway.

The GUARDHOUSE is set into the north-facing curtain wall, flanked by bastions. It is a rectangular two-storey building constructed of tooled Purbeck stone ashlar and red brick with a hipped slate roof. On the north front the lower storey is a continuation of the battered curtain wall; the roll moulding or cordon of the wall continues across the gatehouse, separating the storeys. At the centre is a round-headed carriage archway, which is set into a projecting rusticated surround with projecting imposts and keystones. There is a portcullis slot set behind the archway, which leads to a brick barrel-vaulted entrance passage with a granite floor. The letters FORT MONCKTON are painted in white over a black background above the arch on the north side and beneath them is a glass lantern. On either side of the arch are six square embrasures, two of those to the west have been opened out to form larger openings. The first floor contains seven bays of six-light casement windows, except for two Yorkshire sliding sashes in the fifth and sixth bay. The roof has two corbelled red brick chimneys with clay pots. There are two single-storey red brick additions to the side elevations, positioned on the terreplein; a lean-to against the west wall and a flat felt-roofed extension with two bays of small square windows against the east wall. The south elevation is rendered with a five-bay arcade to the ground floor: the first bay at the west is covered by a single-storey red brick lean-to with timber doors, a sash window and slate roof; the second and fourth bays contain double doorways with segmental transom lights; the third forms the entrance passage; and the fifth bay contains a single timber doorway. There are ten bays of six-over-six sashes to the first floor. Internally the ground floor was not inspected but the first floor has a corridor on the north side with rooms containing modern furnishings leading off to the south. It has a king-post roof. An early C20 octagonal water tower stands on the terreplein immediately to the west of the Guardhouse. It is constructed of red brick with two blind rectangular recesses set into each side, a string course, and corbelling beneath a lead roof. The tower originally supported a metal tank but it was removed in about the 1970s and replaced by the current roof.

The entrance passage leads to the PARADE GROUND of the fort, now surfaced in tarmac as a car park. On the west side is the Former Central Magazine and Former Officer’s Mess (both excluded, see below). An early C20 water tank, which originally held 10,000 gallons, stands immediately to the south-west of the Central Magazine. It is an open tank, circular in plan with low red brick walls.

A CASEMATED BARRACK BLOCK is built into the south-east curtain wall, facing the sea. It is a long rectangular block orientated north-east to south-west with bastions flanking each end. The seaward-facing (south-east) elevation is of tooled-ashlar construction, marking a continuation with the adjoining curtain walls. On the ground floor there are 23 bays comprising 22 blocked round-headed embrasures, which formerly served the casemates, and a single square-headed doorway in the centre that served as a sally port, providing access out onto the beach. The cordon of the curtain walls continues across this block to separate the storeys. On the first floor there are 46 bays comprising both full-height openings, containing six-over-six horned sash windows, and half-height openings, containing casement windows, although several are now blocked. They are set below the eaves of a hipped slate roof. The north-west elevation of the barrack block faces the Parade Ground. It is constructed of red brick laid in Flemish bond with flared headers. On the ground floor are 25 bays of segmental-headed openings to the former magazines; those at the north-east contain large timber-boarded doors with wrought-iron strap hinges but most of the openings at the south-west have been infilled with brick or glazing and contain timber-panelled doors with overlights. The two end bays each contain brick staircases with original wall-mounted hand rails. There are 47 bays to the first floor comprising six-over-six horned sash windows with stone cills and square-headed door openings with timber-panelled doors. Access to this level is provided by a steel and concrete first floor walkway running along the length of the north front. It is covered by a glazed roof and approached by two covered stairways attached to two ablution blocks. There are four ablution blocks along the elevation; two full-height blocks in the centre and two raised blocks towards each end. They are constructed of red brick with sash windows and timber-boarded doors. Internally there are vaulted casemates to the ground floor and a series of former barrack rooms leading off a south corridor on the first floor; these rooms were in use as lecture and demonstration rooms, stores and an auditorium in 1919.

The FORMER OFFICERS’ QUARTERS form two separate buildings adjoining each end of the barrack block at the south-west and north-east, with later extensions. The main elevation of the south-west Former Officers’ Quarters faces the sea and has slate-hung walls with 15 bays of top-hung windows and a hipped slate roof. It is adjoined by two later ranges: a parallel late C20 addition at the north-west constructed of red brick with PVC windows and a hipped-slate roof; and a 1970s extension at the south-west with slate-hung walls, PVC windows and a flat felt-covered roof. These later additions are excluded from the scheduling but the ground beneath them is included. The north-east Former Officers’ Quarters comprises several ranges; two parallel linear ranges with hipped slate roofs extending to the north-east, a cross range with a hipped slate roof extending to the south-east; and a small gabled range facing the Parade Ground. They are constructed of red-brick in Flemish bond with flared headers and sash windows. The cross-range is surmounted by a mid- to late C20 observation tower with a flat roof. The north-east end of these officers’ quarters is now known as ‘Rose Cottage’; the exterior has gauged brick segmental-headed openings containing three-over-six sash windows. This block is adjoined at the north by a c2000s addition (at SZ 61258 97877), which is clad in red brick, slate, and full-height glazing; it is excluded from the scheduling but the ground beneath it is included.

The CURTAIN WALLS and BASTIONS that form the main enceinte or enclosure are constructed of tooled Purbeck stone ashlar with an outer batter beneath a cordon and parapet. The parapet has an earth backing revetted in red brick and is punctuated by embrasures for top-mounted guns originally set on the terreplein. Most of the embrasures are now blocked and infilled in red brick or concrete. Earthen ramps provide access up onto the terreplein from the Parade Ground. At the apex of the north-east, south-west and seaward-facing bastions are surviving C19 gun emplacements with granite races. The south-west bastion also includes surviving remains of three concrete emplacements set into the inner revetment of the parapet. A C20 concrete emplacement on the north-east seaward-facing bastion has been enclosed with PVC ribbon-glazing and a flat roof. Next to several emplacements are vaulted expense cartridge stores and shell recesses, which are constructed of red brick with segmental-headed openings lined with stone.

Surrounding the curtain walls is a flat-bottomed dry DITCH, which varies from about 15m wide at the bastions and up to about 30m wide in the intervening space. The outer edge is revetted in Purbeck stone ashlar to match the curtain walls. Two CAPONIERS extend into the ditch at the north-east and south-west end of the fort where it meets the beach. The north-east caponier is partially ruinous but that to the south-west is largely intact. The caponiers are each laid out to an arrow-head plan and constructed of red brick laid in Flemish bond with flared headers and stone dressings. The brickwork forms barrel-vaults covered by gabled tiled roofs. There are two tiers of square embrasures for small arms along their length, as well as pointed arched door openings and blocked round-headed openings in the gable ends.

A COVERED WAY is situated beyond the ditch and is c20m wide with an outer edge or parapet and revetted in red brick. It conforms to the plan of the ramparts and bastions except for two triangular RAVELINS sited in front of the curtain walls; that to the west survives largely intact but that to the north has been partly denuded and truncated by the re-alignment of the approach road and construction of a late C20 guardhouse. The west ravelin is a triangular earthwork embankment revetted in red brick with a firing step for infantry. The covered way was originally spanned by ten traverses formed by low-walled embankments to prevent flanking fire, but only one survives adjacent to the south-west bastion; the positions of the others are indicated by rectangular bays in the outer wall of the covered way, which allowed access around the traverses. Access onto the covered way is provided from two stone stairs set into the outer wall of the ditch at the west of the fort. The lines of the parapet at the apexes of the covered way extend down in long slopes beyond the fort as a GLACIS, continuing for a distance of about 75m to the outer works.

The OUTER WORKS to the fort comprise a series of water defences adapted from natural features. At the west is an artificial lake formed in the course of the River Alver, which is nearly 150m wide. It was originally about 420m long but a c50m section at the north end was infilled in the 1970s and landscaped as part of the golf course. In addition a narrow causeway was created about mid-way along its length. The western edge of the lake is delimited by a bank up to c1m high, upon which is a modern roadway (Military Road). The southern edge is marked by a slight bank, whilst at the east the boundary has retreated from its original extent, which matched the triangular outline of the western ravelin; a low gully indicates its former position. A wet moat extended eastwards from the north end of the lake to form the northern edge of the glacis. This has been infilled at the west where it survives as a slight depression but to the east it is a flat-bottomed ditch up to c2.5m deep, c29m wide across the top and c15m wide at the bottom. The course of the former wet moat broadly matches the outline of the northern ravelin and north-east bastion of the fort.


The FORMER OFFICER’S MESS is a single-storey rendered and gabled building with round-headed sash windows, which was built in about the early C19 and extended from a single rectangular block (marked ‘Recreation Room’ on late C19 plans) to form a larger red brick cruciform plan building in the early C20. It is Grade II-listed and therefore not included in the scheduling, but the ground beneath it is included. The single-storey red brick gabled building (at SZ 61166 97811) immediately adjacent to the north-east corner of the Former Officer’s Mess was first erected in the c1970s and probably re-built at a later date with round-headed sashes, a porch under a side gable and slate roof. It is excluded from the scheduling, but the ground beneath it is included. On the terreplein behind the west curtain wall is a large two-storey red brick and concrete accommodation block (at SZ 61122 97860) that was built in c2009 replacing a 1960s building. It is also excluded from the scheduling but the ground beneath it is included.

The CENTRAL MAGAZINE was built in the late C18 and is a single-storey red brick barrel-roofed building with two pedimented doorways either side of a Diocletian window on the main (south) front. It is Grade II*-listed and not included in the scheduling, but the ground beneath it is included.

At the north-east end of the ditch to the curtain walls are three c1990s or c2000s buildings, stepped-off the ditch wall; a rectangular red brick building with ribbon-glazing and a hipped roof (at SZ 61248 97930), a C-shaped building with a flat roof set into the corner of the ditch (SZ 61281 97944), and a rectangular building with a flat zinc-covered roof (SZ 61282 97912) next to the caponier. These three buildings are excluded from the scheduling but the ground beneath them is included.

Several later C20 and early C21 buildings have been constructed on the covered way and the glacis at the north-east of the site, including a large two-storey red brick accommodation block with a hipped slate roof (SZ 61329 98009); all these buildings are excluded from the scheduling but the ground beneath them is included.

In addition the following are excluded: all modern fences or fence posts, gates and gateposts; the paved, tarmacadam or concrete surfaces of all modern roadways, pathways or car parks; all benches, bins, lights and lamp posts; security cameras and poles; flag poles; golf flags and poles; all railings and bollards; drains and drain covers. However, the ground beneath all these features is included.


The contents of this record have been generated from a legacy data system.

Legacy System number:
HA 436
Legacy System:


Books and journals
Moore, David, Solent Papers No. 8 - The Stokes Bay Defences, (2010)
Moore, D, Solent Papers No.13 - Fort Blockhouse and Fort Monckton, (2014)
Saunders, A D, Fortress Britain, (1989)
Saunders, A D, Fortifications of Portsmouth and the Solent, (1998)
Williams, G, The Portsmouth Papers No.30: The Western Defences of Portsmouth Harbour 1400-1800, (1979)
1797 site plan, Portsmouth PRO, Reference: MPHH 226
1883 site plan, Portsmouth PRO, Reference: WO 78/5011 (reproduced by the Palmerston Forts Society in Fort Log 16)
1892 site plan, Historic England Archive, Reference: MD95/06393 and MD95/06394
1919 site plan, Historic England Archive, Reference: MD95/06395
Cocroft, W, Historic England Introductions to Heritage Assets: Artillery Defences (2011), available at
Saunders, A, English Heritage MPP Monuments Class Description: Forts 1660-c.1865 (1998)


This monument is scheduled under the Ancient Monuments and Archaeological Areas Act 1979 as amended as it appears to the Secretary of State to be of national importance. This entry is a copy, the original is held by the Department for Digital, Culture, Media and Sport.

End of official listing

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