Fort Blockhouse and the Submarine Mining Establishment
A tower referred to in old documents as a 'Bulwark' or a 'Blockhouse' stood on the shingle spit on the west side of the entrance to Portsmouth harbour from early times. By 1417 this tower, built from timber and known as Ye King's Blockkehouse, secured the western end of a chain closing the entrance to the harbour. About 1538, as part of Henry VIII's re-fortification plan, another Bulwark close to Blockhouse (referred to as Lymdens's Bulwark) was built, alongside or over the ruins of the tower, to mount eight guns. In the reign of Elizabeth I the site was upgraded and Sir Bernard De Gomme (1667) added to the battery to mount 21 guns during the reign of Charles II. Between 1845 and 1848 Blockhouse was again updated and modified Its armament was improved by adding a row of guns in a second tier. The Times (Aug 21 1845) reported that when finished this fort "will be one of the best fortified positions on the coast". In 1847 The Times stated that "The fort at Blockhouse, when completed, will be one of the hansomest and best fortified of its size in England".
Blockhouse viewed from Capstan Square: Print 1846
|Blockhouse viewed from Old Portsmouth: Print 1855
Sitting to the west of the narrow entrance to Portsmouth Harbour, Fort Blockhouse was an ideal site for the Submarine Mining Establishment. Submarine minefields formed an important part of the defence of the UK's ports and dockyards. The first Submarine Mining Company was formed in 1871 and a permanent R.E. stores section was created to supply the equipment. Fort Gilkicker was used for submarine mining from 1873 when a test room was built at the fort, but Fort Blockhouse became the main Submarine Mining Establishment for Portsmouth in 1873. Work on the Fort Blockhouse Submarine Mining Establishment was commenced in January 1877 and completed in July 1877. It consisted of a complex of a connecting up shed, cable tanks, a pier and crane. A quarter master's office and a clerk's office were added in 1884. Workshops, a loading shed, boat sheds and a cable shed were completed by 1879. The workshops included a fitter's shop, machine shop, painter's shop, carpenter's shop, a connecting up room, a test room, battery roomand an experiment room. On the parade of Blockhouse Fort itself were a loading shed and a loaded mine store whilst two of the sea casemate magazines were converted to guncotton stores. An 18inch tramway was built to allow the mines to be run from the case store on the parade of Blockhouse Fort through North Bastion to external buildings and to the pier where they were loaded on to laying vessels. A branch ran out through the main entrance to Blockhouse to asist with bringing in supplies. In 1886 a pit for testing primers was built next to North Bastion. In 1888 the pier was extended and beach cable tanks were added close by. In 1890 and 1891 a case store, chart and test rooms were added.
In 1880 The Times reported that the 4th Company of Royal Engineers, Submarine Miners, were quartered in Fort Blockhouse. This same year it was decided to improve the accommodation in Fort Blockhouse and Fort Monckton in order to hand them over to the Royal Engineers to form a school of submarine mining. In 1884 the school of submarine miners moved out of Fort Monckton and was wholly based in Fort Blockhouse. Also in 1884 it was proposed to build a pier at Stokes Bay for the school of submarine mining". In 1885 The Times reported that the 34 Company Submarine Miners stationed at Blockhouse were preparing to move to Malta. By 1892 a Submarine Mining Establishment had been constructed at Stokes Bay. From 1892 to 1907 the Portsmouth Militia (Submarine Miners) was based in Blockhouse. In 1898 Fort Blockhouse was modernised with the addition of a 12pr Q.F. Battery. The facility at Blockhouse became superfluous when the Navy took on responsibility for Submarine Mining in 1905. At that time the facility, consisting of 14 store buildings and casemates; one large mine store; two boat sheds, wet guncotton stores; electrical fitting room; carpenter's, fitter's and blacksmith's shop; four cable tanks; coal sheds; eight other rooms or buildings and a large pier, was valued at £20,000. in May 1905 it was reported in The Times that the Naval Establishments Inquiry Committee visited Blockhouse where the new depot for submarine boats was being constructed.
The Submarine Mining Establishment Establishment at Fort Blockhouse in 1886. Note the 18-inch gauge tramway.
The Submarine Mining Establishment Establishment at Fort Blockhouse in 1891.
Fort Blockhouse at the entrance to Portsmouth harbour in 2009.
Submarine Miners at Gosport in January 1897
According to a plan in the National Archive dated 1955 the whole of Fort Blockhouse was transferred to The Admiralty in January 1931 on the condition that it it would provide the War Department with accommodation when necessary. The fort served for many years as part of the shore base HMS Dolphin, the home of the Submarine Service. The submarine school remained at HMS Dolphin until 1998/99 when the name of the site reverted to Fort Blockhouse.
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