down to the riverside. It was the only point along a fourteen-mile stretch of the river between Cliffe to the west and Grain to the east where a landing could be effected, due to the marshes along the rest of the shoreline. A fort situated at that point could thus provide an effective defence against an enemy attempting to land here. It also served to fill the gap between the upriver forts (Cliffe, Coalhouse and Shornemead) and those at the mouth of the Medway (Grain and Garrison Point). As an 1869 report noted, the fort was constructed "to prevent an enemy landing at the only accessible point for the purpose of attacking Chatham Dockyard from the north". The land for the fort was bought by the War Office in 1861 for £1,639, but it was not built until 1867. The estimated cost of constructing the fort was reported in 1869 to be £27,343 (equivalent to £ today). It took the form of a semicircular arc of seven casemates facing the river with a defensive ditch in front. Each casemate was faced in granite with magazines below providing ammunition via hoist shafts. A defensible block constructed of Kentish ragstone closed off the arc and provided the fort's domestic accommodation. The fort's main entrance is at the centre of the defensible block. A small stone-paved parade ground occupied the centre of the fort. After it was built, the ground behind the fort was raised and made into a glacis. On the roof of the fort, accessed from the ground level by two spiral staircases, there was an observation post protected by a banquette (an elevated step to facilitate rifle fire against attackers at close range). Operational history Slough Fort was initially armed with seven 7-inch rifled breech loaders (RBLs) positioned in the casemates. It was manned by three officers, one NCO and 75 other ranks. Between October 1889 and December 1891, a pair of wing batteries were constructed from concrete on either side of the fort, with a range finder position being added to the fort's roof. The new batteries accommodated two 9.2-inch and two 6-inch breech loaders on disappearing mountings, allowing them to recess below ground level once they had fired. These were much more powerful and longer ranged weapons than the old RBLs and were capable of engaging a battleship at a substantial distance. The old RBLs were removed. The