Details

The monument comprises a section of Chatham Lines at Chatham Gun Wharf known
as the Barrier Ditch. It represents the early 19th century modification of
the most southerly section of the defences on the Gun Wharf, and includes the
terminal end adjoining the eastern bank of the River Medway. The earlier
phase of The Lines at the Gun Wharf appears to have followed a different
alignment, located in the area of the New Gun Wharf to the south of the
monument. This comprised a ditch with internal rampart crossed by a
drawbridge carried road. The gate was defended to its south by a substantial
ravelin (a defended outwork) and glacis (a bank sloping down from a defence
where attackers were exposed to fire). By 1786 the ravelin was no longer
extant although the ditch and rampart continued on the same line but this was
to be replaced in the early 19th century by a new alignment to the north. The
monument includes the intersection of the primary and secondary phases of The
Lines.
Historical sources indicate that the Gun Wharf section of the modified
alignment was completed and the ditch reveted in brick by about 1805. The
ditch ran north-south for approximately 80 feet (24.4m) immediately adjoining
the river before making a right-angled turn to the east. Here a counterscarp
gallery of three casemates was located to provide lines of fire along the
ditch in both directions. The ditch then continued in an easterly direction
for a further 300 feet (91.2m) where it was crossed by a drawbridge carrying
the Chatham road from the south into the military zone. A guardhouse, known
as the Lower Guard House and which partly survives, had the dual role of
protecting this external gate as well as regulating traffic onto the Gun
Wharf. A rampart was located on the inner face of the ditch with a small
square bastion (now lost) located at its terminal end. The bastion is likely
to have been a later addition to the early 19th century defences. A
cartographic source shows it as a small rectangular structure with a
banquette (an infantry firing step) and parapet on all sides, approached by a
pair of steps.
The western two thirds of the monument do not survive above ground but are
preserved under public open space. The western angled termination and bastion
had been lost by 1932 by which time the lower end of the Barrier Ditch had
been infilled and the re-entrant in the river frontage removed by the wharf
being extended across the corner. Observations during late 20th century river
wall repairs and landscaping confirmed that the Barrier Ditch survived intact
in this area but had been backfilled. The eastern third of the monument is
partially located under Riverside 1, a building constructed within the
Barrier Ditch at some point between 1900 and 1932.
The basement of Riverside 1 has been constructed using the scarp and
counterscarp of the Barrier Ditch to form its north and south external walls.
The battered ditch sides are visible internally surviving to a maximum height
of 2.3m. The building's east wall is formed by the western elevation of the
1876 fixed bridge carrying Dock Road into the militarised zone. This replaced
the earlier drawbridge. The two bridge arches (now bricked-up) are visible in
the basement. The terminal end of an east-west stretch of rails is located in
the floor of the north east basement room (the current boiler house). The
gauge of the rails is 18 inches (0.46m) wide. Although only a short stretch
(1.45m) is visible, the rails survive under the remaining length of Riverside
1 to the west and have also been deliberately preserved under the full width
of the adjacent car park to the west.
A brick reveted banquette survives to the north of and immediately adjoining
Riverside 1. The parapet stands approximately 4m above the present ground
level. Behind and to its north is the infantry firing step, and below this a
sentry path. The rampart survives for a length of approximately 28m east-west
and would have originally terminated at its eastern end, adjacent to the
western elevation of the Lower Guardhouse. This relationship has been
interrupted by the insertion of a modern porch.
The surviving elements of the Lower Guardhouse comprise ground and basement
levels surmounted by a later 19th century first floor. At ground level the
north elevation exhibits two contiguous arched openings, the most westerly of
which has been altered with the insertion of a later window and door. This
section is blocked and inaccessible. To the east is a north-south barrel
vaulted room. The south wall contains a blocked fireplace flanked by two
arched niches. In the south east corner is an arched recess leading to a
blocked square-headed door. This is the entrance to a short tunnel which runs
under Dock Road to Fort Amherst to the east. The basement level is accessed
by an arched entrance in the north elevation, located under the present
ramped road onto the Gun Wharf. This is also a brick built north-south barrel
vaulted room with a rammed earth floor. It comprises 5 unequal bays each
separated by a brick arch. Two brick pillars support the roof in bay 4 and
are presumed to relate to the later addition of the first floor. The room is
approximately 15m in length north-south and extends beneath the Gun Wharf
access road and barrel vaulted room above. Its south elevation is part of the
scarp of the Barrier Ditch and contains a blocked casemate. This would have
provided covering fire for both drawbridge and ditch.
All modern ground and road surfaces, telegraph poles and modern street
furniture are excluded from the scheduling, although the ground beneath them
is included. All existing services and their trenches are excluded from the
scheduling although the ground around and beneath them is included. The first
floor of the Lower Guard House is excluded including the modern floor,
although the ceiling of the ground floor is included. The 20th century
structure of Riverside 1 is excluded from the scheduling although the
historic fabric which forms the north, east and west elevations of the
basement is included. The floor of the north east room immediately adjoining
Dock Road (the current boiler room) is included as is the ground beneath the
modern basement floor to the south and west, although the modern floor itself
is excluded. The rampart to the north of Riverside 1 is included. The late
19th century former ordnance building to the north-west of Riverside 1, known
as the Blacksmith's or Machine Shop, is excluded, although the ground beneath
its south end is included.

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

Source: Historic England

Reasons for Scheduling

The Chatham Lines were first constructed in 1755 as a defensive
fortification to protect the landward side of Chatham Dockyard and the
subsequently associated barracks. The pre-existing civilian settlement of
Brompton was incorporated into the militarised zone.
A Board of Ordnance report of 1708 discussed the strengthening of
fortifications at a number of sites, including Chatham, and was followed
by a land purchase and survey in the early 18th century. The 1755
construction was probably a response to an invasion threat during the
Seven Years War between Britain and France (1756-1763), with Chatham
Dockyard a potential target for French attack. Tensions between the two
countries had been building specifically in relation to their dealings
with the colonies. Britain declared war in May 1756 and France retaliated
by seizing British colonial bases. Conflict also took place in the
Mediterranean and Northern Europe.
Designed by Captain John Peter Desmartez and constructed by military
personnel under the direction of Hugh Debbieg, The Lines comprised an
earth rampart and unrevetted ditch enhanced by bastions. The continuous
circuit ran from the north end of the Dockyard (the `Ligonier Line') to
the Gun Wharf to the south (`Cumberland Line'), adjoining the east bank of
the River Medway at either end. The ditch was 12.4 feet (3.7m) wide at
the base, battered to a maximum width of 24 feet (7.3m). From the base of
the ditch to the top of the internal rampart was a maximum of 15 feet
(4.5m). A series of horizontal stakes (known as `fraises') were inserted
on the scarp at a height of 7 feet (2.1m) from the base of the ditch to
prevent the enemy scaling the defences. The glacis was approximately 19
feet (5.7m) wide, measured from the edge of the ditch. The internal
rampart comprised a banquette (an infantry firing step) and was designed
in two different forms, one with an additional sentry path behind the
banquette. Three gates (one a sally port), approached by drawbridges and
protected by gatehouses, allowed access to the enclosed garrison area.
The Lines were intended to perform both a defensive and offensive
function. Exploiting advantages in the local topography and deliberately
enclosing substantial areas of open ground, the design was a deliberate
response to the capabilities of contemporary artillery. The open ground
within The Lines formed a protective zone to absorb enemy fire directed at
the Dockyard and barracks, as well as providing essential areas for troop
encampments and exercises. The Lines also served as a physical barrier,
shielding the garrison from enemy gaze prior to any counter attack. The
garrison could then advance through the defences to engage the enemy in
the open area of the field of fire or indeed further into Kent.
The Lines were subsequently extended, realigned in places and reinforced
in the late 18th century (at the time of the American War of Independence
of 1775-1783 when France allied herself with the rebellious North American
colonists). A third construction phase, a substantial rebuild in the early
19th century, was again in response to a perceived threat from France in
the build up to and during the Napoleonic Wars (1803-1815). Modifications
in the 1770s and 1780s strengthened both ends of The Lines, with Amherst
Redoubt constructed at the south end and Townsend Redoubt at the north.
Amherst Redoubt, in conjunction with Prince William's Redoubt, Belvedere
Battery, Spur Battery and the `Couvre Port' (a covered gate), developed
in the 1790s into the Fort Amherst complex, a rare survival of a
British Napoleonic fort in its original form. The Lines were extended
northwards to St Mary's Creek and this new section was known as the `Lower
Lines'. Outlying forts, such as Forts Clarence and Pitt constructed to
control the roads and approaches to Rochester Bridge, further enhanced the
defences. The ditches and ramparts were also revetted in brick as the
unrevetted defences had proven unstable. This was completed by 1805.
The Lines were never tested and were declared obsolete by the 1860 Royal
Commission, which concluded that the defences were redundant, given
changes in military technology. A series of new forts were therefore
constructed to protect the dockyard (the same approach also being taken to
the defence of the dockyards at Portsmouth and Plymouth). At Chatham seven
were constructed in an arc about one and a half miles from the dockyard.
(Forts Borstal, Bridgewoods, Horsted, Luton, Darland and two infantry
redoubts at Twydall). However, The Lines continued to play a role as a
control point and demarcation line between the military garrison and
surrounding civilian settlements. Elements found a new use, such as the
internal open space which became pleasure gardens for the officers. The
Lines also continued to perform a military training function and were used
to test defensive and offensive techniques and strategy prior to foreign
campaigns.
The Lines were reused both during the First and Second World Wars. Between
1914-18 they functioned as a training ground for trench warfare and
mining. During World War II they were heavily re-fortified, with the ditch
serving as an anti-tank obstacle in a line of Medway defences. Air raid
shelters, anti-aircraft guns, an emergency reservoir and at least one
pillbox and spigot mortar were added at this time. The Lines were also
used for Home Guard training.

The section of The Lines at Chatham Gun Wharf is a critical component of the
early 19th century defences and represents the southern terminal of the
circuit. The monument survives in good condition and includes archaeological
evidence of the earlier 1750s defence and of one of the defended gateways
into the militarised zone. The relationship of The Lines and the Gun Wharf is
also of considerable importance to our understanding of Chatham's military
function.

Source: Historic England