Fort Cumberland is located on the southeastern corner of Portsea Island on the shingle spit known as Eastney Point. It was built to control the entrance to Langstone Harbour to the east, and to improve the defenses of Portsmouth Dockyard to the west.
The significance of Eastney Point as a defensive outpost was well recognised as early as 1716 when an earthwork battery was built on the site to defend Langstone Harbour. In the mid 1740s, following the Jacobite rebellion, the threat of a French invasion was very much in the mind of William Augustus, the 2nd son of George II and Duke of Cumberland.
He, therefore, undertook a review of the nation’s defences and the first proper fort was built on Eastney Point. Construction began in 1747 under the watchful eye of Ordnance Engineer and designer John Desmaretz. The first fort was star-shaped in plan and was constructed with rubble stone revetting. Gun embrasures for the larger guns were concentrated to the south and south-east on the seaward side of the fort. Each point of the five-pointed star allowed defensive fire in all directions, leaving no blind spots where attackers could hide. Following the War of American Independence and the deteriorating political relations in England a review of Portsmouth’s defences was carried out by Charles Lennox, the Duke of Richmond. In this review he recommended that Fort Cumberland should be rebuilt. Plans for the new fort were submitted in 1782, and works commenced in 1783, however work was very slow and costly with the fort taking some 29 years to complete in 1812. The second Fort, and the one which remains on the site to this very day, was a pentagonal fort in plan with projecting defensive earthworks (bastions) at the end of each length of curtain wall, and was built mainly of brick and Portland limestone. Construction of the new fort was hampered by shortages of raw materials and the lack of labour. The labour was a mixture of contract and convict. These convicts were housed in prison hulks which were moored in Langstone Harbour.
The fort has vaulted casemates within the curtain wall; these were incorporated to counter the advances in artillery which meant free standing buildings were vulnerable to shelling. These casemates housed the men, stores and powder magazines in the relative safety of the curtain wall. Life in these brick barrel-vaulted rooms would have been very unpleasant and crowded, with as many as 30 men to a casemate. It is in two such casemates that the Portsmouth Distillery has made its home.
The fort was equipped with an impressive array of artillery throughout it’s active life, but perhaps the most impressive was William Armstrong’s Hydropnuematic 6″ breech loading gun. The fort was armed with 6 of these from 1890 and they were housed in disappearing gun carriages.
During the twentieth century the fort was the base of the Royal Marine Artillery Howitzer and Anti-Aircraft Brigade. After the second world war the fort became a training establishment, these training activities continued until 1973 when the fort was decommissioned and handed back to the government, which is when English Heritage and now Historic England took on stewardship for this monument.