Monument MPM45 - Fort Cumberland

Perhaps the best surviving example of 18th century defensive architecture in Britain. The present fort was built between 1786 and 1812, replacing an earlier fort constructed on the same site 1747-50. The fort protected the entrance to Langstone Harbour and also acted as an eastern defence to Portsmouth Dockyard. It was used by the military until the 1970s and is now an archaeology research establishment for Historic England.

Perhaps the best surviving example of 18th century defensive architecture in Britain [3, 10], the present Fort Cumberland was built between 1786 and 1812, replacing an earlier fort that stood on the same site.

The original fort designed by John Peter Desmaretz was built 1747-50 on the orders of the Duke of Cumberland as part of a project to upgrade Portsmouth's defences [9]. The first fort was built in the form of a 5 angled star and was constructed of earth with rubble revetting [1, 8, 9]. Situated on a spit of land at Eastney the fort was built to protect the entrance to Langstone Harbour from a French attack/invasion, replacing an existing gun battery [9, 10]. It also acted as an eastern defence to the Dockyard [9]. The only structures that survive from the original fort are the guardhouse [MPM500] and the storehouse [MPM501] (converted into a hospital in the mid-19th century) [8,9].

The fort was reconstructed between 1786 and 1812 in its present form as a wide pentagonal shaped rampart with 5 arrowhead shaped bastions linked by curtain walls, a dry moat and glacis and a ravelin to protect the main gate [3, 9, 10]. This second fort was larger and included casemates within the curtain walls for men, stores and powder magazines [9]. Casemates around the main gate housed a pay office, guardhouse and detention cell. Surviving graffiti in the latter includes tallies of days, drawings of ships and a quotation from the Old Testament [9]. Original fire-grates survive in several of the rooms formerley used for accomodation in the casemates along the landward sides of the fort [10].

During the 19th and 20th centuries additional buildings were constructed within the site. These included a cookhouse [MPM2027], officer's quarters [MPM502] and wagon sheds [see MPM2047] constructed in the 19th century and a garage and motor transport shed in the 1930s [9].

Fort Cumberland contains a rare example of a High Angle Fire battery built in the 1880s. This type of battery was designed to drop shells from a height onto armour-clad warships and was one of only six constructed in the UK. Large curved gun emplacements for hydrophneumatic guns on disappearing gun carriages were added on the seaward side of the fort in the 1890s [9].

The fort became the headquarters of the Royal Marine Artillery in 1859 after being transferred to the Admiralty from the War Department. During the First World War the Royal Marine Howitzer and Anti-Aircraft Brigade were based there. In 1923 it became the home of the Mobile Naval Defence Organisation and after the Second World War housed the Royal Marines Technical Training Wing. The fort was bombed during an air raid on the 26th August 1940 and eight men were killed in a shelter in one of the casemates. The Ministry of Defence left the fort in 1975 and it became the home of the Central Excavation Unit. [9]

A number of archaeological investigations have been carried out at the site, the results of which are either recorded below or on the individual HER monument record to which they relate.

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Originally built as a 5 angled star fort in 1746 by the Duke of Cumberland, the fort was rebuilt as a bastioned pentagonal form in 1794. It was vacated by the military in 1973 and is now a research establishment for Historic England. [1]

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Fort. 1746. By the Duke of Cumberland, reconstructed 1786 by the Duke of Richmond, some alterations and additions C19. Stone and brick. Originally built in the form of a 5 angled star, then reconstructed 1786 in its present form with wide pentagonal shaped rampart with 5 sharply angled bastions at each of the points, a dry moat and glacis and 1 ravelin. Ramparts are faced externally in stone with brick parapets and segmental arched gun ports behind which are deep tunnel-vaulted brick casemates covered with several feet of earth. HISTORY: the fort is a direct descendant of the bastioned fortress pioneered in Italy in late C15 and the last fortress to be built here marking the final development of this type of design in Britain. It is perhaps the best piece of C18 defensive architecture left in Britain. Scheduled Ancient Monument. (Balfour A: Portsmouth: London: 1970-: 22; Lloyd DW: Buildings of Portsmouth and its Environs: Portsmouth: 1974-: 62; The Buildings of England: Pevsner N & Lloyd DW: Hampshire and the Isle of Wight: Harmondsworth: 1967-: 428).

Selected Sources
Books and journals
Balfour, A, Portsmouth, (1970), 22
Lloyd, D W , Buildings of Portsmouth and its Environs, (1974), 62
Pevsner, N, The Buildings of England: Hampshire and the Isle of Wight, (1967), 428

[3]

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The position of the line of the rampart and ditch belonging to the first Fort Cumberland of 1747 was confirmed during a watching brief on a service trench between casemates 36 and 13 in 1997. This passed to the north of an earlier Guardhouse. The line of the rampart was visible as a dark clay loam soil. This was easy to distinguish from the clean sandy gravel of the ditch fill. [2]. Further evidence relating to the rampart and ditch to the original fort was recording during geophysical surverys conducted between 2019 and 2023 (see below).

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A research excavation carried out by Historic England in 2015 to investigte water ingress in casemates 36 and 37 revealed elements of the construction of the casemates and repairs made following Second World War bombing. [4]

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Part of the brick counterscarp wall of the dry ditch at Fort Cumberland was encountered during a watching brief in 2001/2 in a trench excavated for services for lighting located along the side of the road between the right curtain wall sally port and the main gateway into the fort (north-west). The wall had been partially dismantled in the 1940s when the access road was constructed.

During the same watching brief gravel layers that had made up the surface of the parade ground at the fort were recorded in trenches excavated for paths and lighting around the fort. The trenches were located to the north-east of the perimeter road of the parade ground, the disabled parking bays by the Laying Out Shed, in front of Houses 1-4 (former Officer's Blocks) and north-west of the Motor Transport Shed. The stratigraphy of the layers was thought to show where the surface of the parade ground had been renewed periodically. In the trench north-east of the perimeter road of the parade ground it was though that the layering may also have represented, in part, where earthworks from the first fort had been levelled.

See Monument records MPM2040, MPM2041 and MPM2042 for additional features recorded during the watching brief comprising two pits, linear cuts relating to services and layers relating to gardens outside the former officer's blocks.

[5]


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The footings of the corner of casemate 9 in the Left Bastion were exposed during the excavation of a telecom cable trench in 2000. The trench was excavated to a depth of 0.5m. The wall footings consisted of roughly squared limestone blocks stepped out from the line of the wall quoin. They were situated beneath a limestone plinth at the base of the brick wall to the casemate/bastion.

The remains of a short length of railway track and a 19th century brick culvert are recorded under MPM2043 and MPM2044.

Layers of gravel representing the sequence of development of the gravel Parade Ground and a c2.7m wide cemented limestone and brick rubble layer which appeared to have been laid as hardcore of the road surface leading from the perimeter road to the Left Bastion were also recorded during the watching brief.

[6]


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Second World War bomb damage to the counterscarp wall and the upper parapet wall of the covered way in the north-east of the fort was recorded during the excavation of two bomb craters in 1999. Both walls had been badly damaged in a German raid on the 26th August 1940. The excavations revealed evidence of late-18th and early-19th century construction methods employed in the construction of the counterscarp retaining wall. Further information is recorded in the English Heritage Research Report. The bomb craters are recorded as HER Monument records under MPM2045 and MPM2046.


Counterscarp Wall (north of the apex of the central bastion)
A large section of the counterscarp wall had been demolished by the blast from the bomb as far down as the Portland limestone foundation. Although the limestone blocks had withstood the damage they had collectively been forced into the ditch as the wall line had buckled.

The excavation of the bomb crater revealed elements of the construction of this section of the counterscarp. Three fairly substantial red brick walls up to 1.20m wide ran perpendicular to the line of the counterscarp wall acting as buttresses. The space in between each wall had been infilled with beach gravel. The northern and central wall were 3.24m apart and the central and southern wall 3.4m apart. The southern and northern walls survived to the height of the top of the counterscarp but the central wall had been badly damaged by the bomb and only survived to 0.5m above the limestone foundation. The bricks were the same type as those used to construct the defences between 1793 and 1812. This brickwork and gravel infill had contained the damage inflicted by the bomb.


Parapet Wall (of the covered way to the north-west of the central bastion)
The bomb had made a c5m long breach in the wall which had broken into sections. The upper sections had been blasted over a metre through the material that made up the covered way, and the lower less damaged sections had buckled and been forced up to 0.8m out of alignment. The brick sections had slumped towards the centre of the bomb damaged area.


The two traverses on the north-eastern covered way were also surveyed and recorded during this phase of works. The southern traverse was rebuilt following the survey. The northern traverse remained in the same condition as when surveyed and a proposal for its stabilisation was being developed at the time the report was produced (2001).

[7]

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A number of anomalies were identified across the site during geophysical surveys conducted between 2017 and 2023 using Ground Penetrating Radar and Magnetometer. The surveys detected a range of services (e.g. water pipes, electricty cables etc) together with evidence of structural remains associated with the forts defences and temporary buildings shown on 1940s aerial photography. The results are summarised below but the survey report should be consulted for full details.


Evidence of the survival of the outer edge of the rampart and ditch to the original 1747 fort was identified as a subtle dipping linear anomaly (66) that crossed the parade ground east-west with a distinctive change in orientation. Two fragmented rectilinear anomalies either side on the same orientation may have represented associated structural remains. The majority of this feature had been built over by the later defences.

North moat to Ravelin Shed
A sub-circular amplitude anomaly may have represented a sump or cistern associated with historical drainage. This may also have been the root ball of a former tree.

A series of anomalies in the moat may suggest the location of former buildings within this area. However, these may not be historic and could be related to temporary accommodation erected for security personnel for the 75th anniversary of the D-Day landings in 2019.

Several anomalies were thought to relate to temporary buildings visible on post-war aerial photography (1946). Two of these anomalies were recorded in the moat on the western side of the fort [see MPM2131]. A rectilinear anomaly to the south of the vehicle entrance to the Ravelin shed was also thought likely to relate to a temporary building shown on the photographs [see MPM2132].


Parade Ground
East of 66 were two fragmented rectilinear anomalies relating to former buildings shown on the 1946 aerial photographs that matched the dimensions of the laying out shed [see MPM2133].

Several anomalies [see MPM2134] were thought likely to have been associated either with the supply of historic services to the hospital building [MPM5010], possibly water supply/drainage, or an adjacent temporary building. A rectilinear feature of the same dimensions and location as one of these anomalies is visible on a 1946 aerial photograph surrounded by a fence suggesting this structure may have been a kind of pond, tank or cistern. Another anomaly within this area may represent a ditch or path.

Fragmented structural remains found south of the parade ground either in association with concrete building pads or on the same orientation, matched the location of a range of former buildings shown the 1946 aerial photographs [see MPM2135]. Linear anomalies probably represented services although one anomaly may have been associated with railway tracks recorded during the excavation of a telecom cable trench [MPM2043].

Other anomalies in the parade ground may have been related to bomb damage.


[8]

<1> Fox, Russ, 1989, Fort Cumberland, SZ69NE3 (Excavation archive). SPM22.

<2> Hampshire County Council, 1998, Archaeology in Hampshire Annual Report for 1997 (Bibliographic reference). SPM201.

<3> Historic England, The National Heritage List for England (Index). SPM35.

<4> O'Hara, Paddy, 2016, Fort Cumberland, Portsmouth, Excavation Above Casements 36 and 37 (Bibliographic reference). SPM605.

<5> Fellows, David, 2002, Report on the excavations resulting from improvements to the paths and lighting at Fort Cumberland (Bibliographic reference). SPM613.

<6> Fellows, David, 2001, Report on the Telecom Cable Trench Watching Brief at Fort Cumberland (Bibliographic reference). SPM614.

<7> Fellows, David, 2001, Report on the Excavation and Survey of Two of the Bomb Craters at Fort Cumberland (Bibliographic reference). SPM615.

<8> Clements, Megan, Linford, Neil & Payne, Andrew, 2023, Fort Cumberland, Eastney, City of Portsmouth: Report on Geophysical Surveys, May 2017 to May 2023 (Bibliographic reference). SPM649.

<9> Historic England, 2023, Fort Cumberland (Bibliographic reference). SPM650.

<10> O'Brien, Bailey, Pevsner, Lloyd, 2018, The Buildings of England Hampshire: South (Bibliographic reference). SPM585.