Stack Rock Fort – Milford Haven, Wales - Atlas Obscura

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Stack Rock Fort

Milford Haven, Wales

This 19th-century island fort built to protect against an invasion by sea. 


Stack Rock Fort sits on a rocky island about 800 yards off the western coast of Wales near Milford Haven. Built between 1850 and 1852 and later upgraded, it has been under private ownership but effectively abandoned for almost a century. Recently sold, this imposing two-in-one fort is now awaiting a new lease of life.

The original idea for a fort on Stack Rock actually goes back to Thomas Cromwell and 1539. The English lawyer, statesman and chief minister to King Henry VIII proposed the fortification of the island to protect the Milford Haven Waterway (a natural harbor), but nothing ever came of the plan. Similar proposals and surveys of the island followed in 1748 and 1817, but it wasn’t until the mid-1800s that any plan came to fruition.

The Royal Dockyard at Pembroke Dock, located along the Milford Haven Waterway, was deemed in need of further defenses against attack from the sea, especially in light of a possible invasion of Britain from France under Napoleon III. Due to its strategic location near the mouth of the waterway, Stack Island was once again in the spotlight, and construction of a fort was completed in 1852.

The original three-gun fort housed three 32-pounder guns, with one 12-pounder for protection of the walls of the dock. The original tower was upgraded with casemates a few years later, and several rifled muzzle loader guns were installed. It was again extended in 1870 when the large circular ‘second’ fort was built around the original tower, after which it could hold a garrison of up to 175 troops and 5 officers. The fort’s importance waned over the next two decades, however, and by 1895 most of the outdated artillery had been removed, although it did retain a key role in covering a nearby minefield. During World War I it was manned by just a small number of soldiers, with only two QF guns remaining, and eventually disarmed completely in 1929.

Stack Rock Fort was first put up for sale in 1932, at which time it sold for just £60. It was again listed for sale in 2015, this time for £150,000, but it proved to be a tricky place to sell. Considering the island location, and the lack of sewage, water, and power, it’s perhaps unsurprising that this impressive ‘colosseum at sea’ took a while to sell and resisted development plans.

In 2018, the fort was once again put on the market, and in late 2020 it was sold to a private buyer with plans to make the location accessible to the community as a ‘living ruin’. So if you like the idea of an off-grid island fort complete with gun towers, perfect for surviving the zombie apocalypse but perhaps a little rough around the edges, then Stack Rock Fort might be taking visitors soon.

Know Before You Go

Stack Rock Fort is located near the mouth of Milford Haven Waterway in West Wales. The fort is privately owned and fully secured, so access is only possible with the permission of the owner, and any visits much be arranged in advance.

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