West Blockhouse, together with East Blockhouse, were originally built by Henry VIII to protect the entrance to Milford Haven Harbour. The later West Blockhouse Fort was built between 1854 and 1858. This was one of four forts built at this time, the other three being Thorn Island, Stack Rock and Dale Point. These forts were all coastal artillery forts, and in the case of West Blockhouse, it was armed with six guns and accommodation behind for forty two officers and men. By 1859 we know that the battery mounted six 68-pdr SB guns. These were upgraded to six 80-pdr RML gun in 1875. With the Royal Commission Report in 1860, Western Blockhouse was given very low propriety as an ‘out of date’ works.
West Blockhouse has a barrack block, with magazine in the basement. The land approach is protected by a dry ditch and drawbridge. The guns are in a fan shaped platform to the front of the barrack block. There is a small outbuilding, with the old water tank on it, which was later used as an engine room.
In 1889 consideration was given to using West Blockhouse as a Practice Battery. Between 1901 and 1907 this Practice Battery mounted four 5-inch BL guns. A practice battery of two 3-pdr QF guns was mounted on the roof of the barracks. All trace of this battery have been lost with subsequent refurbishments.
Between 1901 and 1902 West Blockhouse Battery was built just outside the West Blockhouse to mount three 6-inch BL guns and two 9.2-inch BL guns. This new battery took over the role of West Blockhouse which became redundant as a coastal defence facility.