Earthwork defences at Priddy's Hard


Heritage Category: Scheduled Monument

List Entry Number: 1010741

Date first listed: 01-Jul-1991

Date of most recent amendment: 09-Jan-1992


Ordnance survey map of Earthwork defences at Priddy's Hard
© Crown Copyright and database right 2018. All rights reserved. Ordnance Survey Licence number 100024900.
© British Crown and SeaZone Solutions Limited 2018. All rights reserved. Licence number 102006.006.
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The building or site itself may lie within the boundary of more than one authority.

County: Hampshire

District: Gosport (District Authority)

Parish: Non Civil Parish

National Grid Reference: SU 61494 01038


Legacy Record - This information may be included in the List Entry Details.

Reasons for Designation

Portsmouth and Gosport have arguably the finest collection of defences in the country dating from the 15th to the 20th centuries. The defences of Priddy's Hard, along with the adjacent length of fortifications behind Royal Clarence Yard, are the best surviving lengths of 18th century fortifications around Portsmouth Harbour. The defences are also important as a component of the gunpowder store and depot developed at Priddy's Hard; whilst the late 18th century barracks, guardhouse, and Commandant's house have long since disappeared, the complement of buildings and earthworks still remaining represents a remarkably complete survival of a late 18th century ordnance complex, dating from the classic age of British sea-power. Whilst only the core buildings and earthworks are protected by listing and scheduling, the whole complex can be considered to be of national importance.


Legacy Record - This information may be included in the List Entry Details.


The monument includes the earthwork defences at Priddy's Hard, the area containing the earthworks surrounding the magazine inside the northern angle of the defences, and the area just outside the southern end of the defences which contains the earthworks around the immediately adjacent shell rooms and the Ready Use magazine. The monument does not include the range of shell rooms and their associated earthworks further west and along the shore of Forton Lake, or the outlying magazine earthworks prominent in the area inland and to the west of the defences. The monument is a component of the defences around Portsmouth Harbour and, more specifically, of the powder magazine and depot at Priddy's Hard. Other components of the depot are protected as listed buildings: the magazine and stores (Grade I), the magazine (Grade II*), the main office (Grade II), the three stores on the Camber (all Grade II), the Camber Basin (Grade II), and the Ready Use magazine (Grade II). The fundamental principles of national defence changed little during the period which saw the first installation of heavy ordnance guns in warships in the 16th century until the First World War and the arrival of airpower. British strategists agreed that the first line of defence must be the main fleet waiting at its war base or cruising off the enemy's bases to intercept his ships if he put to sea. A second line of defence was the coastal fortifications. In wartime the third line was the field army. During this period, each threat to the country, whether real or imagined, tended to produce a flurry of activity which was usually not maintained once the immediate crisis had passed. Nevertheless, there were several locations where permanent fortifications were maintained and there is a degree of strategic continuity and defensive inevitability associated with a number of coastal towns and harbours, leading to a superimposition of works of several periods on the same site. Strategic harbours and anchorages, especially the main naval dockyards of Portsmouth, Plymouth, Chatham and Sheerness, have acted as important focal points for such defences. Fortifications of the 18th century drew upon the work of the French military engineer Vauban. In England, attention was focussed less on individual forts and more on providing continuous lines of defence around dockyards and a few coastal towns, such as Gosport. These lines were generally simple in form with little defence in depth. The bastionned defences protecting Priddy's Hard are an important survival of the 18th century fortifications built to protect the naval installations around Portsmouth Harbour. Portsmouth dockyard had been refounded by Henry VII in 1495 but it only developed into a major fleet base in the 18th century, rebuilt and extended in the last forty years of the century to become one of the greatest naval bases in Europe. Artillery defences to protect Portsmouth Harbour were built in the late 15th century, augmented in the 16th and 17th centuries, most notably in the reign of Charles II. Charles II's Chief Engineer, Sir Bernard de Gomme, was responsible for reforming the defences in the 1660's and 1670's and built land defences to protect the town and dockyard from assault by an enemy force landing in the neighbourhood. He concentrated his defences in a bastionned trace around Portsmouth and part of his work survives at Long Curtain and the King's Bastion. On the Gosport side of the harbour, de Gomme began work in 1677/8 on a defence line round the town and on the construction of Forts Charles and James and the predecessor of Fort Blockhouse. The town defences remained weak and incomplete at his death and in 1748 the Ordnance Board began an extensive programme of rebuilding and strengthening them. Around 1757 earthwork ramparts were extended north to protect the site of the future Priddy's Hard, this length being built to deny the vacant ground to an enemy seeking to bombard the dockyard from there. In the early 1770's the Board of Ordnance established its powder magazine and depot behind the rampart with its two demi-bastions. To strengthen the latter, a covered way [which is a level pathway in front of the ditch, but lower than and covered by a parapet, where infantry could wait to break up an assault] and glacis [which is a bare slope on which the attacker was completely exposed to fire] were added between 1778 and 1790; the brick tunnel through the rampart is also thought to have been added at this time. At the beginning of the 19th century the two loopholed brick walls were added at each end of the moat. The defensive line now survives as a substantial 6m high and 22m wide rampart associated with two protruding bastions, a moat with an average width of 30m and depth of 4.5m, and a glacis slope; these defensive features have been subsequently altered by the insertion of later structures and blast earthworks associated with the powder depot. The northernmost bastion survives as an irregular pentagon with its base in the main line of the rampart. It has maximum dimensions of 90m by 67m with the surrounding banks being up to 6m high. A large red brick Magazine building survives within the interior of the structure. The second bastion has a similar ground plan character to the first, though there is a smaller platform at the outer angle. The maximum dimensions of this feature are 80m by 65m with 6m high banks. At the two eastern internal angles of the bastion are low mounds in which the traces of brick structures are clearly visible. The outer edges of this bastion were utilised as a blast wall for nine inter-war timber buildings, each associated with further blast earthworks which were built in the moat and up against the outer face of the bastion. None of the original bastion was destroyed by this later reuse, though its appearance has been considerably altered. A further three units were built up against the southern length of the rampart, each again associated with additional blast walls. These units all lie within the moat, which is flat bottomed, 30m wide and 4.5m deep. The moat is considerably wider in the area between the bastions, though there is no trace of a ravelin [an isolated outwork within a moat], or other defensive works, which are often found in this type of location. In the area immediately outside the northern bastion the moat has been used as a refuse heap and a narrow pond betrays some limited cutting of deposits. An access road to this rubbish dump has caused some limited damage to upper levels in the area immediately north of the northern bastion. The various inter-war structures erected within the moat would appear to have no foundations and damage to underlying deposits is likely to be insignificant. On the outer edge of the moat the covered way is visible at a number of locations. It is best preserved at the northern end of the earthwork where it survives as a clear platform between the moat and glacis. Between the two bastions the low 0.4m high earthwork, along which a trackway now leads, probably represents the partly demolished parapet, which survives more clearly opposite the southern length of the southern bastion. The glacis situated on the outer edge of the moat is most complete opposite the northern bastion where it survives as an earthwork with a triangular ground plan sloping gently away from the moat for 40m. The northern part has been cut through by a later track and the angle destroyed by a building. The glacis opposite the southern bastion also extends for 40 metres from the moat edge, though it is less clearly defined. Between the bastions, the glacis is only about 15m wide though in the area south of the southern bastion it is 30m wide. A short length of the glacis also survives at the northern end of the defence where it has been partly damaged by a later building. The following buildings are excluded from the scheduling: the magazines, the shell rooms, and the various later buildings constructed in the moat of the earthwork. Also excluded are the road surface running along the southern and middle part of the moat, the footbridge across the moat leading to the frontal angle of the southern bastion, and the surface of the road which leads through the earthwork at its northern end. The land under all these buildings and features is included in the scheduling.

MAP EXTRACT The site of the monument is shown on the attached map extract.


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

Legacy System number: 20210

Legacy System: RSM


Books and journals
Brice, M H, Stronghold, A History of Military Architecture, (1984)
HCC Historic Buildings Bureau, , Towards a Conservation Strategy for Priddy's Hard, Gosport, (1990)
Saunders, A D, Hampshire Coastal Defence since the Introduction of Artillery, (1977)

End of official listing