This building began in 1874 as a gun battery to defend Dover from attack by enemy ships. Beginning in 1891, the battery was decommissioned and the structure adapted so that, by the First World War, it fulfilled four main functions: Fire Command Post, controlling the coast artillery protecting Dover and the Straits of Dover; Port War Signal Station, controlling Royal Navy ships entering and leaving the harbour; Royal Navy signalling and wireless communication to and from ships and other signal stations; and early warning of attack by ships and aircraft. The large central concrete structure was added in 1941 to give protection from attack by enemy aircraft. It conceals the brick Fire Command Post of 1905 and part of the Port War Signal Station of 1914, while the rest of that station remains exposed on the left. Still partly visible on the right are remains of the original gun battery. In the First and Second World Wars, the building was essential for the safety of Dover as a vital garrison and naval base.