Slough Fort was one of the more than seventy forts recommended by the Royal Commission Report in 1860 (Palmerston Follies). The Fort was built between 1861 and 1868 at a cost of £27,343. Slough Fort mounted seven 7-inch RBL guns which were not installed until 1871 when they were arguably redundant. The guns were behind granite walls with iron shields on the first floor, with their magazines on the ground floor level below.
In 1888 because of recommendations made in the Imperial Defence Plan, the front of the Fort was covered with earth to conceal it, and the gun deck level all removed. The old magazines, which had been below the guns, were converted into barrack accommodation. The height of the fort was reduced by almost two storeys to make it more difficult to see as part of the move towards dispersion of fortifications. The old magazines were used as accommodation, and the new roof level was used for small arms.
In 1895 two wing batteries (Right and Left) were added each with one 6-inch BL on HP mounting and one 9.2-inch on HP mounting. Three 3-pdr Q.F. guns were added, probably on the roof of the Fort itself. The magazine and 6-inch HP position still remains buried, although the 9.2-inch position has been uncovered.
In 1905 the Right Battery (East) was upgraded to mount two 9.2-inch BL guns. The old magazines were modified and there was a single dual-purpose shell/cartridge hoist at each end.
The old 6-inch HP gun on this flank is presently being excavated (2023).
In 1912 the Fort was decommissioned. It was to be used again in both World Wars.