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Stack Rock Fort

A Grade II* Listed Building in Herbrandston, Pembrokeshire

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Latitude: 51.7025 / 51°42'9"N

Longitude: -5.0921 / 5°5'31"W

OS Eastings: 186435

OS Northings: 204946

OS Grid: SM864049

Mapcode National: GBR G4.YW6R

Mapcode Global: VH1RX.PGCP

Plus Code: 9C3PPW35+25

Entry Name: Stack Rock Fort

Listing Date: 4 March 2004

Last Amended: 4 March 2004

Grade: II*

Source: Cadw

Source ID: 82592

Building Class: Defence

Location: On Stack Rock island in Milford Haven some 2.7km S of Herbranston village.

County: Pembrokeshire

Town: Milford Haven

Community: Herbrandston

Community: Herbrandston

Locality: Milford Haven

Tagged with: Fort

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Island fort in the middle of Milford Haven, built in several phases 1850-71. The initial building was a three-gun tower of 1850-2, like those by the dockyard at Pembroke Dock, and built to complement the contemporary forts at Dale, West Blockhouse and Thorn Island. They were rendered obsolete by the change from smooth-bore to rifled guns and the launch of the French ironclad ship La Gloire in 1858 prompted a complete review of defences. This report in 1858 recommended four new land forts on the inner Haven (at Popton, South Hook, Hubberston and Chapel Bay) and the rebuilding of Stack Rock as a much larger fort with guns in casemates as well as open-air. There were to be two tiers of 19 casemates and 16 open air guns above, 54 in all, a massive armament for the Haven (Fort Hubberstone by comparison was to have 12 guns in the casemates and ten above). Between 1859 and 1861 foundations were laid for a structure to encircle the original gun tower, intended to be of limestone and granite. In 1861 the plans were changed to granite piers with iron shields between and the basement floor and magazines were completed by 1863 when the whole scheme was revised. There were to be 16 eighteen-ton guns in a single tier in the front face and seven smaller guns on two floors in the gorge, facing into the Haven. The upper tier was to be accommodation for 4 officers and 152 men, and then on top were to be three turrets each with two massive 25-ton twelve inch guns. This scheme was built 1864-71. In 1872 the 16 ten-inch guns in the casemates and the seven seven inch guns in the gorge were installed and rope mantlets fitted to the shields. The roof turrets for the 12 inch guns were never built.
By 1874 the ten-inch guns were obsolete but the size of the casemate shield ports prevented installation of larger guns, so the armament remained in position until dismantled in 1922.
The fort was abandoned after 1918 and finally sold for £60 in 1932. It cost £96,840 to build.


Island fort, in two parts, a gun-tower of 1850 in tooled grey limestone of two storeys, to trefoil plan with rounded elevations, coped parapet and flat roof, completely surrounded by an added ring in rock-faced limestone and silver granite, comprising a casemates for guns in the main part occupying three-quarters of the circle and a recessed two-storey block on N side, to same roof line. From the exterior the inner tower is not visible. The casemates comprise sixteen large deeply-recessed cambered-headed openings with iron shutters, the recesses square-headed. Masonry in large square blocks with raised coping, high base of smaller rock faced blocks sloped outward in lower half, with bull-nose string-course below casemates, and flat roof with concrete gun emplacements. The ends of the casemate ring are rounded and return in to the 2-storey N range which has a curved 3-bay front with widely spaced small square windows and centre square-headed door, raised above high battered plinth.


Interior not accessible, the rear of the two-storey N range has brick walls with broad cambered-headed openings, glazed in small panes with mullions and transom. The upper floor is accessed by an iron balcony.

Reasons for Listing

Included at II* as a major piece of Victorian military architecture, part of the outstanding group of forts in the Haven. Scheduled Ancient Monument PE 334.

External Links

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