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.

Source: Historic England

Reasons for Scheduling

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.

Source: Historic England

Sources

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)

Source: Historic England