A remnant of ''The Royal Commission on the Defence of the United Kingdom', established in 1859 in response to a perceived threat of invasion from France's Napoleon. Whom it was believed posed a danger of an amphibious landing in Pembrokeshire as part of a wider threat to the security of Britain. A chain of coastal artillery forts was designed, but ultimately only this fort at Tenby was constructed. The government compulsory purchased St Catherine's Island for construction, and undertook the mammoth task of lifting solid granite blocks onto the island to build the fortress. It was, however destined for alteration. The gun shields were finally installed in 1886, and in that year, a report to the Defence Committee described the 9 inch guns as "useless". It never saw military action, and by 1907 it had already been decommissioned and converted into a lavish private residence. Since then it has been re-garrisoned twice and used as an anti aircraft battery in both world wars, turned back into a private home, and converted into a fully fledged zoo, which left the fort derelict after its closure in the late 70's, prompting a lengthy wait until it was restored and opened to the public around five years ago. A colourful history to say the least..