With their formidable firepower, their main purpose was to guard the dockyards from potential attack from landing areas on the Hampshire coast.

In August 1914, 9th (Heavy) Battery Royal Garrison Artillery was formed at the fort as part of the raising of Kitchener's Army.

[5] Although modern life has encroached on the fort, its fabric remains largely unaltered and the parade ground, gun ramps and moated keep can all be viewed.

The new forts could be more easily adapted to the terrain and allowed a greatly increased number of heavy guns mounted on the ramparts to prioritise offence over defence.

The nineteen heavy guns of the main armament were mounted on the ramparts reached by two ramps on the enclosed parade ground in the middle of the fort.