Fort Verdala was built between 1852 and 1856 as defensible barracks for the British Garrison. The Fort was surrounded by casemates walls, and until the 1890s, 24-pdr SB guns provided local defence. The perimeter wall made use of the old Santa Margherita Bastion and St Helens Bastion built by the Knights of St John.
Used as a Prisoner of War Camp during World War I, it came under Royal Navy Control in 1918 and was used as barracks for the Royal Marines. It was used as a RN store and school for the children of RN personnel.
The barracks provided troops to defend the adjacent St Clements Retrenchment.