Somerton Fort was built from 1861 - 1864 following the Royal Commission on the Defence of the UK. It was built slightly inland and protected Milford Haven and the surrounding harbours and approaches.
The fort is hexagonal in plan surrounded by a wide escarpment. Entrance is via a drawbridge and tunnel. The fort garrisoned around 130 men and was intended to house 32 guns. However the guns were never installed and it was used for training only. Underground features include magazines, casemates and stores. Some of these were used as air-raid shelters and later as D-Day ammunition stores in World War II.
The fort has scheduled protection and is in private hands. Access is not allowed but Sub Brit got permission to visit in 2003.