Site Records

Site Name: Hoo Fort

Medway Estuary
North of Gillingham
Kent
OS Grid Ref: TQ797703

Sub Brit site visit 9th September 2007

To protect the gunners, a shield (designed and developed by Captain Inglis and Lieutenant English, both of The Royal Engineers), was placed over each embrasure; the gun firing through an aperture - a direct imitation on land of a battleship's armour. The shields were made up of 'alternate layers of five-inch wrought-iron plates and five inches of wood. The usual thickness was made up of three layers of iron with two intermediate layers of wood.

These alternate layers of wood and iron resisted penetration much better than a single thickness of ten or fifteen inches of iron - the wood also lessened the effects of shock on the mountings, thus enabling the shields to remain in position even after a direct hit. The gunners were further protected by a curtain of woven rope called a mantlet, this stopped splinters from the shield injuring the gun crew should it receive a hit. The shields were set into arches in the outer granite wall - these arches are known as 'casemate arches'. Those shields facing the main channel are much thicker than those which face landward.

The total cost of both forts was £171,936, far exceeding the original budget of £100,000. The increase was largely due to the difficulties in preparing adequate foundations and the extra expense (£30,900) of providing the shields. In trying to assess the capabilities of the forts, one must realise that when they were built, Europe was in a state of turmoil and any addition to Britain's defences would have been beneficial. Britain's ability to survive the period from 1859 to 1914 without an invasion attempt was due partly to the inaction of the French and partly to the deterrent value of the fortifications. This deterrent value completely justified the Commissioners' recommendations for the construction of the forts.

Although only a few guns could be brought to fire at a ship at any one time, the penetrative power of a 9-inch R.M.L was such as would force an enemy to think twice about an attack. The forts practised gunnery for many years (one of the guns cracked in its casemates and this was reported in ‘The Chatham Observer’ on the 25th January, 1879); The forts were disarmed and abandoned before the First World War, The Royal Artillery Corps Care and Maintenance Unit looked after the sites until about 1920. In 1930 experiments were carried out at Hoo Fort, and to a lesser extent at Darnet Fort, to ascertain the likely damage to underground magazines caused by accidental explosion of stored cordite. The accommodation casemates were used for the above ground experiments whilst the magazines were used for the below ground experiments. Some damage was recorded and the final test caused the collapse of the magazine roof.

In the two World Wars the forts were used as observation posts, and platforms were built on top in the form of brick pillboxes which are still in existence but at Hoo there is no longer any access to the top of the fort. Hoo island remained in MOD hands for many years but is now owned by Medway Ports.

Source: Medway's Island Forts by R. Crowdy published by Medway Military Research Group, part of the Amhurst Heritage Centre.
For more pictures of Hoo Fort see Underground Kent web site

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