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Fort Blockhouse

Hob Uid: 462035
Location :
Hampshire
Gosport
Gosport
Grid Ref : SZ6260099300
Summary : Fort Blockhouse, a coastal battery rebuilt in 1708 from a chain tower of circa 1421 and a battery of 1667. It was again rebuilt in the mid 19th century with a casemated battery. The battery was disused before the First World War, but was armed with a 4-inch anti-aircraft gun in 1916 . It mounted two 6-pounder and two 12-pounder quick-firing guns in the Second World War and was eventually taken over as part of a submarine base, 'HMS Dolphin'.
More information : (SZ 626993) Fort Blockhouse (NAT) (1)

Fort Blockhouse (SZ 626 993)

One of the original defences of the principal entrance to Portsmouth Harbour, Blockhouse began as a boom tower erected in the reign of Edward VI to hold one end of a boom chain. It was subsequently improved and enlarged and became known by its present title some time in the eighteenth century. In 1805 it carried fifteen 36-pounder and fifteen 18-pounder guns and was obviously an important work. The 1859 Commission saw no reason to make any changes there, but neither did they recommend the provision of any modern weapons, and it seems that very little was done with the work to bring it up to date. In 1867 its armament still consisted of 32-pounder smooth-bores, and no heavy RML guns were ever installed.

By the time of World War I it had lost its value as a coastal defence work and was in the hands of the Royal Navy, who used it from then on as a submarine depot. Today it forms part of HMS Dolphin. (2)

Still in use as part of HMS Dolphin. (3)

The Henrician tower was in a state of decay by 1585 and although proposals were made to replace it, little seems to have been done. As the Western end of the `harbour chain', it appears to have been replaced by a fixed point or perhaps capstan to hold the chain until de Gomme redesigned the harbour defences. In 1667 he built an L-shaped battery there with 17 or 18 guns facing South-East and 2 South-West. Talbot Edwards reported in March 1707/8 that `this work like the rest is all gone to ruine'. Thus, in 1708 the fort was rebuilt. The South-West side comprised 2 demi-bastions with gateway between them, a moat with drawbridge, a covered-way and glacis. The South-East side held the battery. By 1744 it was again delapidated but was improved to take 24 guns in 1750. Between 1817-20 the West demi-bastion was widened towards the sea and the open seaward battery of 19 guns was enclosed in casements shortly afterwards, and reduced to 13 embrasures. The North-West and North-East sides were still palisaded at this time, but this was remedied by 1832, and these sides were enlarged with casements between 1840-5. By 1863, the fort had reached its final state, with an upper floor battery raised on brick arches, above the lower embrasures on the South-East side. Unlike the other forts in the Gosport area, it was built and extended over a relatively long time span. (4)

Coastal battery. Buildings and gun emplacements remain (but with some slight alterations) [information from 1946 aerial photographs].Alverstoke. (5)

Documented. (6)

Fort Blockhouse located at SZ 626 992. The fort was completed in 1814. By 1902 it was armed with five 12-pounder quick-firing guns. By 1914 this had been reduced to two guns. During the Second World War it was armed with two 6-pounder and two 12-pounder quick-firing guns. These were manned by 125 Battery of 529 Coast Regiment. (7-8)

The building and emplacements remain with some slight alterations. (9)

Sources :
Source Number : 1
Source : Ordnance Survey Map (Scale / Date)
Source details : OS 1:10 000
Page(s) :
Figs. :
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Source Number : 2
Source : Coast defences of England and Wales, 1856-1956
Source details :
Page(s) : 139
Figs. :
Plates :
Vol(s) :
Source Number : 3
Source : Field Investigators Comments
Source details : F1 JGB 04-FEB-83
Page(s) :
Figs. :
Plates :
Vol(s) :
Source Number : 4
Source : VIRTUAL CATALOGUE ENTRY TO SUPPORT NAR MIGRATION
Source details : Portsmouth Papers No 30 Western Defences of Portsmouth Harbour 1400-1800 1979 22-25 (G H Williams)
Page(s) :
Figs. :
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Vol(s) :
Source Number : 5
Source : Migrated Defence of Britain Project database record originally compiled from various sources
Source details : The two databases developed by the Project can be searched on-line through the Archaeology Data Service at http://ads.ahds.ac.uk/catalogue/specColl/dob/index.cfm
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Source Number : 6
Source : Twentieth century fortifications in England, volume 1. Anti-aircraft artillery : England's air defence gunsites, 1914-46
Source details :
Page(s) : 287
Figs. :
Plates :
Vol(s) :
Source Number : 7
Source : Twentieth century fortifications in England. Volume 6.1. Coast Artillery, 1900-1956
Source details :
Page(s) : 167-176
Figs. :
Plates :
Vol(s) : 6.1
Source Number : 8
Source : Twentieth century fortifications in England. Volume 6.2. Coast Artillery, 1900-1956
Source details :
Page(s) : 259
Figs. :
Plates :
Vol(s) : 6.2
Source Number : 9
Source : Twentieth century military recording project: World War Two Coastal Batteries
Source details :
Page(s) : 74
Figs. :
Plates :
Vol(s) :

Monument Types:
Monument Period Name : Medieval
Display Date : Built 1421
Monument End Date : 1421
Monument Start Date : 1421
Monument Type : Boom Tower
Evidence : Structure
Monument Period Name : Post Medieval
Display Date : Modified 1667
Monument End Date : 1667
Monument Start Date : 1667
Monument Type : Boom Tower, Coastal Battery
Evidence : Structure
Monument Period Name : Post Medieval
Display Date : Remodelled 1708
Monument End Date : 1708
Monument Start Date : 1708
Monument Type : Coastal Battery
Evidence : Structure
Monument Period Name : Post Medieval
Display Date : Remodelled 1845-1850
Monument End Date : 1850
Monument Start Date : 1845
Monument Type : Coastal Battery
Evidence : Structure
Monument Period Name : First World War
Display Date : First World War
Monument End Date : 1918
Monument Start Date : 1914
Monument Type : Heavy Anti Aircraft Battery
Evidence : Documentary Evidence
Monument Period Name : Second World War
Display Date : Second World War
Monument End Date : 1945
Monument Start Date : 1939
Monument Type : Coastal Battery
Evidence : Structure, Extant Building

Components and Objects:
Related Records from other datasets:
External Cross Reference Source : Scheduled Monument Legacy (County No.)
External Cross Reference Number : HA 276
External Cross Reference Notes :
External Cross Reference Source : DoB Anti Invasion Database UID
External Cross Reference Number : S0015107
External Cross Reference Notes :
External Cross Reference Source : National Monuments Record Number
External Cross Reference Number : SZ 69 NW 20
External Cross Reference Notes :

Related Warden Records :
Associated Monuments : 238782
Relationship type : General association
Associated Monuments : 462005
Relationship type : Is referred to by
Associated Monuments : 462026
Relationship type : General association
Associated Monuments : 462029
Relationship type : General association
Associated Monuments : 238752
Relationship type : Is referred to by

Related Activities :
Associated Activities : FIELD OBSERVATION ON SZ 69 NW 20
Activity type : FIELD OBSERVATION (VISUAL ASSESSMENT)
Start Date : 1983-02-04
End Date : 1983-02-04
Associated Activities : THE DEFENCE OF BRITAIN PROJECT
Activity type : MEASURED SURVEY
Start Date : 1995-04-01
End Date : 2002-03-01
Associated Activities : FORT BLOCKHOUSE
Activity type : DESK BASED ASSESSMENT
Start Date : 2005-01-01
End Date : 2005-12-31
Associated Activities : LANDSCAPES OF WAR RECORDING PROJECT
Activity type : MEASURED SURVEY
Start Date : 2008-01-01
End Date : 2009-12-31
Associated Activities : GOSPORT HISTORIC CENTRE
Activity type : DESK BASED ASSESSMENT
Start Date : 2013-01-01
End Date : 2014-12-31