Brean Down Fort forms part of a line of defences, known as Palmerston Forts, built across the channel to protect the approaches to Bristol and Cardiff. It was fortified following a visit by Queen Victoria and Prince Albert to France, where they had been concerned at the strength of the French Navy. The Royal Commission on the Defence of the United Kingdom, under direction of Lord Palmerston, recommended fortification of the coast. Brean Down Fort formed part of a strategic coastal defence system covering the channel between the mainland and the islands of Steep Holm and Flat Holm.