Details

The monument includes a circular, casemated battery, set within an unrevetted
ditch and outer glacis, with associated groynes, jetty and the remains of
later, World War II structures.
Hoo Fort is one of a pair of batteries, its twin being Fort Darnet,
constructed on low islands on opposite sides of the Medway channel. Fort
Darnet is the subject of a separate scheduling. They were built during the
1860s on the recommendation of the Royal Commission on Defence, and were
intended to provide an inner line of defence to protect the approaches to the
naval dockyard at Chatham. An additional safeguard, in the form of a
minefield, laid across the channel between the forts, was to be employed in
the event of war. The major fortifications at Grain and Sheerness supplied the
outer line of defence at the mouth of the river. These are also the subject of
separate schedulings.
The substantial, two-tiered battery, measures around 56m in diameter
externally, and stands to its original height of about 10m. The brick-built
structure is faced in granite ashlar, with lower courses dressed in Kentish
ragstone. The upper level, smaller in diameter than the tier below, protrudes
above the lip of the encircling ditch, beyond which, a sloping bank, or
glacis, extends for a distance of up to 30m. Traces of associated timber
structures can be seen along the foreshore to the north east and south of the
fort, including the remains of groynes, and the jetty, onto which supplies and
ammunition were unloaded.
The fort is entered at ground floor level, through a passage on its north
western side, and was approached from the jetty by way of a curving footpath,
crossing the western slope of the glacis. The entrance passage is flanked
internally by two small chambers, which retain parts of the mechanism for
raising a section of the passage floor, designed to act as a drawbridge in the
event of attack. The passage also provides access to the magazine and
accommodation casemates of the lower tier, arranged in concentric rings around
a solid concrete drum at the centre of the fort. The outer ring of magazine
chambers represent the shell and cartridge stores, and are entered from the
magazine passage in front. Lift shafts rise from the passage, enabling the
rapid deployment of ammunition to the gun floors above. A sophisticated
lighting system formed part of the safety features of the magazine and
consisted of a lantern window, set into the wall above the door to each
chamber, and separated from the chamber by a pane of glass. The lamps were
carried across the magazine passage on horizontal, overhead rails, contained
within zinc conduits, and were served by a ring of lamp chambers, accessed
from the barrack rooms beyond. In turn, the barrack rooms are entered from an
open corridor, or light well, which surrounds the central drum. Steps lead up
from the corridor onto the top of the drum, which provided a small, open
parade at centre of the gun level. The gun level contains an outer ring of 11
interconnecting, vaulted casemates, arranged around the parade and reached by
narrow bridges across the light well. The casemates were designed to
accommodate eleven 9in rifled muzzle-loaders, mounted on traversing carriages.
The casemates retain many of their original features, including the iron
shields inserted into the embrasures for the protection of the gunners. Rope
mantlets were also hung behind the shields to reduce casualties from masonry
splinters in the event of enemy fire, and some of their suspension bars and
rings survive. The chamber behind the gun room was intended to provide wartime
accommodation for the gunners, and was enclosed at the rear by a glazed
screen, designed to be removed before the guns were fired. The screens have
now been lost, along with the glazed verandah, originally constructed around
the parade perimeter. The verandah formed part of the rainwater collection
system for the fort, and was supported on hollow cast iron columns, through
which rainwater was fed to a cistern beneath the parade.
Reuse of the fort during World War II is represented by a minewatching post
situated on the roof, overlooking the Medway to the south east. Additional
features beyond the area of the monument include traces of a low circular
earthwork on the northern tip of the island, considered to represent an
initial attempt to construct the fort, and now partly destroyed and submerged
by the river.

MAP EXTRACT
The site of the monument is shown on the attached map extract.
It includes a 2 metre boundary around the archaeological features,
considered to be essential for the monument's support and preservation.

Source: Historic England

Reasons for Scheduling

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 had been set up following an invasion scare caused by the
strengthening of the French Navy.
These fortifications represented the largest maritime defence programme since
the initiative of Henry VIII in 1539-40. The programme built upon the
defensive works already begun at Plymouth and elsewhere and recommended the
improvement of existing fortifications as well as the construction of new
ones.
There were eventually some 70 forts and batteries in England which were due
wholly or in part to the Royal Commission. These 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 visible core
of Britain's coastal defence systems and are known colloquially as
`Palmerston's follies'. All examples are considered of national importance.

Hoo Fort survives well and retains many of its original components, including
its associated glacis bank. When viewed as one of a pair of contemporary
batteries, the fort provides a valuable insight into the wider, strategic
defence of the Medway during the late 19th century, and its later reuse
demonstrates the continued importance of its location in the defence of
Britain during World War II.

Source: Historic England

Sources

Books and journals
Crowdy, R, Medway's Island Forts, (1979)
Gulvin, K R, The Medway Forts, (1976)
Smith, V T C, Strategic Study of Kents Defences - Fort Darnet , (1999)
Other
RCHME, AP Ref: TQ 7970/19 NMR 15096/25, (1994)
Title: Ordnance Survey 25" Kent sheet XX.1 (surveyed 1861)
Source Date: 1932
Author:
Publisher:
Surveyor:

Source: Historic England