Details

The monument includes Horse Sand Fort, a circular 19th century Royal
Commission sea fort lying in the Solent 3.6km south east of Southsea Castle.
Horse Sand Fort was one of a chain of four sea forts in the Solent recommended
by the Royal Commission on the Defence of the United Kingdom in 1860 and
designed to protect Portsmouth dockyard from seaborne attack. Construction
started in July 1861 but was suspended between 1862 and 1864. The fort was
completed in spring 1880.
Horse Sand Fort is circular in plan and includes sea bed foundation walls of 8
ton pre-cast concrete blocks with an inner and outer casing of masonry. At the
sea bed the structure is 73m in overall diameter and the thickness of
the walls is 18m. The area enclosed by the circular walls is filled with
shingle capped with a slab of concrete 3m thick. Above this lies a
basement divided radially into compartments for ammunition and stores and
concentrically by three circular passages. The outermost, the bolt passage,
was to allow additional armour to be bolted on the exterior of the fort.
Inside this the magazine includes 24 shell stores and lifts opening off a
circular central passage and 14 cartridge stores and lobbies off the inner
passage. In the central core steps led down to a laundry, cookhouse, ablution
room and coal store. At a later stage of the fort's development the outer ring
of shell stores was blocked with concrete and the bolt passage filled with
sand in order to increase protection for the magazine. Above the basement are
two gun floors, each of which is fully armoured for its entire circumference.
The lower floor includes the landing stage and entrance in addition to
positions for 24 guns. To the rear of these and their associated powder
serving rooms and occupying the central area of the fort are officers
quarters. The upper floor has positions for 25 guns to the rear of which are
powder serving rooms and soldiers' quarters. The central area of the fort at
this level includes quarters for a lighthouse keeper and officers' servants.
The roof originally supported a lighthouse, ventilators and chimneys. Position
finding stations were added towards the end of the 19th century but were
removed by 1909. Emplacements were then added for three 6 inch breach loading
(BL) guns and later a fire control position, battery commander's post and
naval signal station. The fort was later equipped with anti-aircraft
searchlights and, for brief periods, anti-aircraft guns. The roof also suports
the loading gantry.
Originally it was intended that the five turrets would have been equipped with
two 12 inch 35 ton rifled muzzle loader (RML) guns but these were never fitted
for financial reasons. By 1882 it was proposed to fit 12 inch 43 ton BL guns
in alternate casements on the vulnerable sides of the fort, with six pounder
quick-firing guns in the spare casements. During 1886-1887 some of the
armament began to be fitted and hydraulic machinery was installed to power
operate the mountings for the 12 inch guns, together with hydraulic lifts,
operated by multiple pulleys, to raise the cartridges and shells from the
magazine. Most of the RML guns were removed by 1898, when two 6 inch BL guns
on electrically operated mountings were fitted. These were not a success and
were removed to be replaced by three 6 inch MkVII BL guns on a central pivot
mounting by 1909. Subsequently the armament was reduced and the hydraulic
machinery stripped out. The fort was armed during both World Wars, the last
gun being removed in 1951.
The navigation light together with its associated solar panels and railings
are excluded from the scheduling, although the structures beneath it are
included.

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

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.

Horse Sand Fort is a well preserved example of its class. As part of an
integrated sea based defensive line the massive structure of Horse Sand Fort
provides a visual reminder of the strategic importance of the Solent in the
late 19th century.

Source: Historic England

Sources

Books and journals
Mitchell, G, 'Solent Papers no. 1' in Spit Bank And The Spithead Forts, (1986)

Source: Historic England