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Fort Blockhouse is an existing military establishment in Gosport, and the final version of a complicated site. At its greatest extent in the 19th century, the structure was part of a set of fortifications which encircled much of Gosport.

Today the Fort is surrounded on three sides by water and provides the best view of the entrance to Portsmouth Harbour. It is unique in two respects. Firstly, it was built over five centuries from its original construction as a blockhouse in 1431. Then in 1539 it became a battery, in 1905 a submarine base, 1996 a training site and finally from 2022 a field hospital.
Secondly, it is thought to be the oldest fortified position in the United Kingdom that is still in active military use though coastal fortification was abolished nationally in 1956, and it has been used only for medical purposes since 2020.

Following the burning of Portsmouth during the Hundred Years’ War, money was set aside in 1417 to provide protection for Portsmouth Harbour. A blockhouse was first built on the Gosport side of the harbour in 1431 after authorisation by Henry VI. A chain was strung across the water, from Blockhouse point to a similar tower in Portsmouth, which could be raised to prevent entry to the harbour by enemy ships.
The blockhouse was replaced in 1539 by an eight-gun battery under the orders of Henry VIII after his divorce from Catherine of Aragon. Blockhouse was supported by secondary fort to the south from 1545–1556, named Haselworth Castle, though this was abandoned only eleven years after construction.
A plan to move the dockyard from Portsmouth to Gosport in 1627 never came to fruition, though storehouses for the new docks were built on the site. In 1642, during the English Civil War, the fort was used to bombard Portsmouth, which was at the time under Royalist control.

The Fort Blockhouse Submarine Mining Establishment was founded in 1877, with additional structures added to the Blockhouse complex including a crane and pier, along with a light rail system to move explosives.
Additional administrative buildings were added in 1884, when the site also became home to the School of Submarine Miners. The pier was extended in 1888, and additional rooms continued to be added for storage and tests until 1891. The Portsmouth Militia Division, which had recently been performing experiments with torpedoes that could be launched from a coastal defence at Fort Monckton, also moved to Blockhouse in 1892 and remained until 1907. The two forts were linked with a narrow gauge railway, which also extended to the facilities in Stokes Bay which were still in use for this purpose. The railway survived into the early 20th century.[4] Blockhouse was turned over to the Royal Navy in 1905 and, as HMS Dolphin, it became the home of the Royal Navy Submarine Service. The Napoleonic era defences that had extended out to loop around the west side of the town were removed, in order to facilitate transportation. Between the two world wars, the establishment expanded beyond the lines of the original fort on Blockhouse point.

Looking along Fort Blockhouse battery to the Solent

In 2016, it was announced that Fort Blockhouse would be disposed of by the Ministry of Defence in 2020, as part of a wider package of reductions in defence estate. Surveys were undertaken from January to March 2020 to determine which structures at the site would become listed buildings, and major job cuts took place at the end of the year. The disposal date was later extended to at least 2023, and once more to 2025.
Today Fort Blockhouse remains in use as the 33 military field hospital, under the 2nd Medical Brigade.

A drone view of the Fort Blockhouse estate [credit to Mike Atthis]

As part of the year’s Gosport Heritage Open Days a very few lucky visitors will be allowed to take part in a rare guided tour of Fort Blockhouse grounds and the chapel, which commemorates 7000 submariners who have lost their lives for their country. Visitors will also be able to see unique and stunning views of the Solent and Portsmouth Harbour.

Programmes are out now and BOOKING OPENS AT 9:30AM ON 20 AUGUST 2022

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