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Coastal artillery defences on the Isle of Grain, immediately east and south east of Grain village

A Scheduled Monument in Isle of Grain, Medway

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Coordinates

Latitude: 51.4536 / 51°27'13"N

Longitude: 0.7224 / 0°43'20"E

OS Eastings: 589247.008376

OS Northings: 176255.338973

OS Grid: TQ892762

Mapcode National: GBR QQH.X1G

Mapcode Global: VHKJ0.GQRH

Entry Name: Coastal artillery defences on the Isle of Grain, immediately east and south east of Grain village

Scheduled Date: 6 July 1976

Last Amended: 9 May 2001

Source: Historic England

Source ID: 1019955

English Heritage Legacy ID: 34297

County: Medway

Civil Parish: Isle of Grain

Traditional County: Kent

Lieutenancy Area (Ceremonial County): Kent

Church of England Parish: Grain St James

Church of England Diocese: Rochester

Details

The monument, which falls into six separate areas of protection, includes five
19th century coastal artillery fortifications, including a gun tower, a fort
and three batteries, and later 20th century additions, including two
searchlight emplacements, constructed on low-lying ground on the eastern
reaches of the Isle of Grain, commanding the entrance to the River Medway.
They formed part of the wider Thames and Medway defences and, with the
positions on the opposite side of the channel at Sheerness, provided a fixed,
first line of defence to protect the important naval dockyards and commercial
ports from a seaborne attack.
Grain Tower was constructed in response to fears of a French invasion during
the mid-19th century, and is located on a tidal mudflat which projects into
the Medway channel. The three-storeyed, roughly oval artillery tower, is
brick-built with walls faced in granite ashlar, and is Listed Grade II. Its
design resembles that of the martello towers, built along the south and east
coast of England in the early 19th century. A thick central column rises from
the basement to the top of the tower, from which springs the barrel vaulted
first floor ceiling which supports the gun position on the roof. The first
floor doorway, the lintel of which is incised with the tower's completion date
of 1855, is reached by boat at high tide or, originally, by steps at low tide
approached from the shore by a causeway of concrete block and timber
construction. Cartographic evidence suggests that the causeway was moved from
its original north west to south east alignment to its present east-west
position by 1889.
The first floor provided accommodation for the garrison, with ammunition and
supplies stored in the basement below. An internal staircase rises from first
floor level to the gun platform on the roof, designed to carry one 56-pounder
and two 32-pounder cannon, mounted on traversing carriages behind an
encircling parapet.
In the years leading up to World War I, the tower became the western anchor
point for a chain boom defence across the mouth of the Medway to Sheerness,
and remains of the chain survive around the base of the tower. Remnants of the
fixed, timber section which connected the tower to Grain beach, and extended
beyond the tower towards the central channel, can also be seen at low tide.
The roof of the tower was also remodelled to accommodate the emplacements and
support structures for two 4.7in quick-firing (QF) guns, installed to cover
the boom, and two new magazine chambers were inserted at first floor level.
Much of the southern emplacement survived the further, radical alterations
made to the roof during World War II.
The tower was re-armed in 1940 with a twin 6-pounder QF gun, to deal with
incursions by high-speed German torpedo boats, and a coastal artillery
searchlight emplacement was added to the side of the tower to assist the gun
during night attacks. Accompanying structures include a battery observation
tower located on the roof behind the emplacement and a free-standing barrack
block, constructed on stilts, with access from the tower on its north western
side, providing extra accommodation for the wartime detachment. Many original
features survive from this period, including the remains of an electrically
powered cage lift, installed at first floor level to meet the gun's
requirement for a rapid supply of ammunition.
Grain Fort was added to the coastline during the 1860s, on the recommendation
of the 1859 Royal Commission into the Defences of the United Kingdom
Fortifications, to support Grain Tower and the defences at Sheerness. The fort
consisted of a north-south aligned, semi-circular brick keep, enclosed on its
eastern front by a ditch, and a large, heptagonal earthwork beyond, designed
to support the armament. The western gorge wall of the keep extended to meet
the ends of the rampart, and the compound was completely enclosed by a
substantial outer ditch. The keep provided accommodation on two levels, for at
least 250 men, and was arranged around a central parade. The parade was
entered through a passageway in the gorge wall, defended by two demi-bastions
and approached through a gap in the rampart. The keep was further protected by
five caponniers constructed within the surrounding ditch. Subterranean
passages led from two of these structures, beneath the rampart, to four
caponniers in the outer ditch. The main magazine survives within the north
eastern passage, and was surveyed in 1999. Many of its original fittings
survive, including the remains of the ammunition lift and some of the notices
labelling various components of the magazine. Subsidiary magazines, and
ancillary chambers, were located beneath the terreplein, which was designed to
support 13 heavy, rifled muzzle-loaders (RMLs) and was accessed, via a covered
way, from the inner ditch. The armament underwent a series of upgrades before
the final allocation of two 6.2in guns in World War II for close defence, and
a spigot mortar at each end of the terreplein, traces of which survive. Grain
Fort was decommissioned in 1956 and its appearance subsequently altered by the
demolition of its keep, and the partial infilling of the surrounding ditch.
In addition to this substantial Royal Commission fortification, a series of
open batteries were constructed along the coastline to the south. The first
was built in the 1860s, approximately 1km south of Grain Fort and, originally
known as Grain Battery, was renamed Dummy Battery in 1901. The two positions
were linked by a communications road which was carried on an earthen bank
across marshland to the south of Smithfield Road. The bank survives as an
earthwork, up to 2m high and 4m wide. Two small structures, built at the
southern end of the bank during World War I, are thought to be related to the
telephone system or power supply for the battery. On dryer ground to the
north, the road was carried in a sunken way, protected by the bank on its
seaward side.
The north-south aligned Dummy Battery was defined by a J-shaped earthwork,
enclosed by an outer ditch on its eastern front. The concrete core of the
earthwork originally supported a linear arrangement of 11in RMLs. The weapons
were upgraded to 6in breech-loaders in 1895, and these, in turn, were replaced
by two 4.7in QF guns in about 1904-5, linked by a covered way, with an
underlying magazine, and a battery control post to the south. The main
magazine was protected beneath a large rectangular blast mound to the rear.
The battery was abandoned after World War II, and subsequent earth moving
during the 1950s exposed the concrete core and emplacements, and the ditch
became flooded. The ancillary structures were also demolished at this time,
and their floors can be traced on the ground behind the emplacements.
Major advances in military technology during the late 19th century, led to the
strengthening and modernisation of coastal defence, including the addition of
two new batteries at Grain. The first, Wing Battery, was built immediately
south of Grain Fort in 1895. It is defined by a north-south aligned, broadly
lozenge-shaped bank, enclosing a central, rectangular hollow, entered at its
southern end from the western gorge. The gorge is formed by the road running
south to Dummy Battery. The gently sloping profile of the battery was designed
to be almost invisible to a seaborne attacker, and its surrounding ditch
contained an unclimable fence for added protection. It was equipped with two
11in RMLs and a pair of 4.7in QF guns, arranged in a line along the forward
rampart, with magazines and detachment shelters below. The range finder
positions were located on the rampart to the north and west, and the concrete
remains of these survive. Several structures were added to the central hollow
during World War I, but these were demolished, and the emplacements infilled,
after the site was abandoned in 1956.
Grain Battery was constructed to the west of Wing Battery in 1900, and
remained in use until the 1930s. Its roughly rectangular, earthen mound was
designed to carry a linear arrangement of four 6in breech-loaders on the
terreplein. On its south western front the battery was enclosed by a ditch,
which curves around the southern end of the earthwork, and contained an
unclimable fence which extended to the rear. A slight outer bank was
constructed along its seaward side, to help conceal the ditch from view. The
battery was entered by a road from the north, which passed through a gate in
the fence. It continued behind the forward rampart, providing access to the
guns and their magazines, and to shelters constructed beneath the road. The
support buildings for the detachment were located on its western side, and
these were levelled, and the emplacements infilled, during the 1960s.
The remains of two electric searchlight emplacements, installed before the
outbreak of World War I, survive on the esplanade. Each consists of a small,
rectangular, concrete chamber with an apsidal extension on the seaward side
which housed the lights. The southern emplacement was extended to the rear by
the addition of a small square room.
There is now little trace of the complex system of anti-invasion defences,
including machine gun emplacements and barbed wire entanglements, which were
added to the coastline during both World Wars, although a strip of anti-tank
obstacles survives along the beach to the north of the monument.
A number of features within the area of the monument are excluded from the
scheduling. These are as follows: the modern shed, situated behind the rampart
of Grain battery; all modern fences, railings and gates; modern steps and
benches; the surfaces of all modern paths and the surface of the modern
esplanade, although the ground beneath all these features is included.

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

Source: Historic England

Reasons for Scheduling

As a maritime nation, Britain has traditionally relied upon her navy for
coastal defence, until the rise of air power after World War I. To support
the navy, a system of fixed artillery positions were constructed at strategic
coastal locations to protect important anchorages and ports from a seaborne
attacker. Their construction coincides with periods of potential invasion and
the anticipation of possible hostile raids.
A range of coastal artillery defences are represented on the Isle of Grain,
due to its strategically important position at the mouth of the River Medway,
including artillery towers, Royal Commission fortifications and coastal
batteries. Artillery towers are essentially raised gun positions of simple
form and formed a consistent feature of artillery defence from the late Middle
Ages to the introduction of anti-aircraft emplacements in World War II. The
most extensive use of artillery towers was in the early 19th century when the
specific group of martello towers was built to protect vulnerable points along
the south eastern and eastern coastline, in response to the threat of a
Napoleonic invasion.
From a period spanning some 250 years of coastal fortification, isolated
artillery towers, and their larger, low-level relatives known as redoubts, are
rare nationally, with only about 17 surviving examples. All examples retaining
a diversity of original components are therefore considered to merit
protection. The Royal Commission fortifications are a group of related sites,
established in response to the 1859 Royal Commission report on the defence of
the United Kingdom. This was set up following an invasion scare caused by the
strengthening of the French Navy. These fortifications represent the largest,
and most expensive, programme of defence construction ever seen in Britain,
until the major conflicts of the 20th century, and involved the improvement of
existing fortifications as well as the construction of new ones. There were
eventually some 78 forts and batteries in England, which were due wholly or in
part to the Royal Commission, and most of these survive today. They constitute
a well defined group with common design characteristics, armament and
defensive provisions. Whether reused or not during the 20th century, they are
the most substantial core of Britains coastal defence system, and most
surviving examples are considered to be of national importance.
Additional batteries were also constructed to provide supplementary fire-power
for the existing Royal Commission fortifications during periods of potential
invasion or hostile raids on the coastline, and existing forts were modified
to carry improved ordnance. Wing Battery and Grain Battery belong to a group
of about 23 surviving examples of batteries constructed during the period
between 1895 and 1914, when standardised gun emplacements with integrated
magazines and crew shelters were required for the new breech-loaders and
quick-fire guns. Major technical innovations were also introduced at this
time, including electrical and telephone systems, and batteries began to
incorporate additional components, such as range finder positions, and command
posts.
Despite later modifications, the 19th century coastal defences on the Isle of
Grain retain a significant proportion of their original features, providing
information related to their construction and use. The subsequent remodelling
of earlier features, and the additions made to the coastline during both World
Wars, provide a rare insight into how military engineering and design was
forced to adapt to meet the radical improvements to artillery and the changing
character of naval warfare.
The fortifications at Grain represent a major landscape feature which
developed over a century of continuous military occupation, and the
significance of the monument is further enhanced by its potential amenity
value as an educational resource.

Source: Historic England

Sources

Books and journals
RCHME, , Coastal Artillery Fortifications on the Isle of Grain, (1998)
Other
NMR, 82/713, 0402, (1953)
NMR, OS/66228, 397, (1966)

Source: Historic England

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