Fort Hubberstone, on the west side of Milford Haven, belongs to a series of forts built as part of the inner line of defence of the Haven following the Royal Commission on the Defence of the United Kingdom. Together with Popton Fort on the opposite shore, it provided an interlocking field of fire, and represented the last layer of defence before reaching the Royal Naval dockyard at Pembroke Dock.
Construction began in 1860 and was completed in 1863. It is a large battery, with eleven guns in casemates, eight in an open battery above, with another nine in an open flank battery, and a large barracks to the rear. It is a D-shaped structure, with a bomb-proof roof which protected the barracks and other buildings from mortar projectiles. On its landward side, it was protected by a deep ditch, and on the seaward side by a counter-scarp gallery. The associated casemate battery is located further down the headland and separated from the fort.
The fort was abandoned after World War I as a consequence of the Haldane Reforms. A 1919 proposal to convert the structure into social housing came to nothing. World War II saw the fort once again in active use, when it was used as an air raid shelter and army camp for American military personnel.
On a good site, the fort has fallen into disrepair. Under the ownership of Milford Haven Port Authority, there were various unsuccessful plans to restore the structure. The site is not currently open to the public, and has been the scene of non-fatal injuries to trespassers.
References:The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.