Cliffe Fort

Cliffe Fort
close to Cliffe-at-Hoo, Kent
View of the south-east corner bastion of Cliffe Fort
Cliffe Fort
Coordinates	51°27′49″N 0°27′21″E / 51.463608°N 0.455871°E / 51.463608; 0.455871
Type	Fortification
Site information
Owner	Brett Aggregates
Open to the public	No
Condition	Derelict
Site history
Built	ca. 1861–70
Built by	United Kingdom
In use	1870–1950s
Materials	Concrete, granite
Battles/wars	First World War, Second World War

Cliffe Fort is a disused artillery fort built in the 1860s to guard the entrance to the Thames from seaborne attack. Constructed during a period of tension with France, it stands on the south bank of the river at the entrance to Cliffe Creek in the Cliffe marshes on the Hoo Peninsula in North Kent. Its location on marshy ground caused problems from the start and necessitated changes to its design after the structure begin to crack and subside during construction. The fort was equipped with a variety of large-calibre artillery guns which were intended to support two other nearby Thamesside forts. A launcher for the Brennan torpedo—which has been described as the world's first practical guided missile—was installed there at the end of the 19th century but was only in active use for a few years.

Cliffe Fort saw about 60 years of usage as an artillery fort, from its completion in 1870 to its disarmament in 1927. It was repurposed during World War II to serve as an anti-aircraft battery on the approaches to London. The fort's military career ended when it was sold off after the war to the owners of a neighbouring aggregates works. Today it lies derelict, overgrown and heavily flooded. It is not accessible to the public and is in a poor and slowly deteriorating condition which has led it to be listed as an "at risk" heritage asset.

By the late 1850s, Britain and France were locked in an arms race. A new generation of increasingly accurate and powerful guns had been developed (of the Rifled Muzzle Loader (RML) and Rifled Breech Loader (RBL) types), mounted on fast-moving, manoueuvrable steam-powered ironclad warships such as the French La Gloire and the British HMS Warrior. Such vessels posed a serious threat to the important naval installations on the Thames, including the victualling yards at Deptford, the armaments works of Woolwich Arsenal, the shipbuilding yards at North Woolwich, and the magazines at Purfleet. It was not possible for large warships to reach central London, as the river was not yet deep enough to take ships of more than 400 tons above Deptford. However, as the American Civil War was soon to show, it was quite possible for the warships of the day to run past forts and attack up coastal rivers.