Stokes Bay Lines The Stokes Bay Lines were part of the great Victorian fortification of Portsmouth Harbour under Lord Palmerston . In 1857 Major Jervois had proposed a complex system of moats ( ditches ) , ramparts and batteries to close off the gap between the new fort at Fort Gomer , and the earlier fort at Fort Gilkicker , and Fort Monckton . This defensive moat was to become the ‘ Stokes Bay Lines ’ . Construction and purpose . The Stokes Bay Lines were constructed to protect the southern approaches to Gosport from a beach landing at Stokes Bay . The Lines consisted of a ditch with a protecting rampart that ran from the Browndown Batteries in the west to the glacis of Fort Monckton in the east . Four batteries were constructed to protect the various branches of the ditch . No . 1 Battery also protected the road to Browndown . No2 Battery held the main sea - facing armament for protecting the deep water anchorage at Browndown Point and also had a casemated battery of guns to fire eastwards along the main branch of the ditch towards Alverbank . No . 3 Battery , at the end of Jellicoe Avenue ( then Village Road ) held a battery of guns to fire westwards towards No . 2 Battery . No . 4 Battery was an isolated work behind the redan that protected the railway to Stokes Bay Pier . No . 5 Battery was the eastern most one consisting of a ' D ' shaped rampart with associated expense magazines and gun emplacements . In 1878 the Royal Engineers diverted the River Alver into the Stokes Bay moat at No . 2 Battery . This was to ensure that there was always sufficient water within the defensive ditch . The level of water within the ditch was controlled by a large sluice adjacent to Number 2 battery whilst penstocks at various points along the ditch allowed precise control of the water levels . When the Stokes Bay Lines were completed by 1870 the peninsula of Gosport was effectively secured against attack from the west thereby protecting Portsmouth with its harbour and dockyard . The cost of constructing these lines was calculated in a report of 1869 to be £75 , 120 . The Stokes Bay batteries today . Nothing remains of the rampart and moat that protected the rear of the Browndown Battery , west of No . 2 Battery . Half of No . 1 Battery was demolished in the 1930s when the Browndown Road was widened . A portion of it remains to the south of the road with much of the concrete revetments and parapets still visible in the gardens of the chalets . The tunnel connecting No . 1 Battery to No . 2 Battery still exists in the gardens of the chalets . The expense magazines and gun emplacements have been demolished . No . 2 Battery is a grade II listed building and it is the best preserved of the Stokes Bay Batteries . Gosport Borough Council purchased the Battery in 1932 from the Home Office for £1 , 500 . In 1933 the parade of the site became a caravan park and in 1939 the Council moved their records from the town hall to the Battery for safe storage . During World War Two the military used the battery . In 1947 it was being used by the Special Armament Development Establishment ( S . A . D . E . ) based in Fort Gomer . In 1950 the Battery was in use by the 7th Royal Tank Regiment Amphibious Wing . The Military agreed the release of the battery in November 1951 . The moat around it was filled in 1956 leaving the channel connecting the River Alver to the sea intact . In 1982 Gosport Council converted the casemates and magazines of no . 2 battery into a nuclear bunker ( Civil Defence Command Post ) at a cost of £30 , 000 . When this idea was abandoned the battery was left vacant until a local volunteer group opened the east facing casemates in 1994 as a Summer Exhibition Centre . The centre gun embrasure was converted to a doorway . The west casemates have had their wooden partitions removed allowing them to be used for storage and parking for the chalets . The two 6 - inch gun emplacements are intact on top of the battery but are not accessible . The concrete pits for the Moncrieff carriages can still be seen beneath the later 6 - inch B . L . emplacements . In 2011 Gosport Borough Council agreed the use of the casemates as a small museum by the Historical Diving Society . Nothing of No . 3 battery remains . No . 4 Battery has been completely destroyed . The site is a stable and paddock for horses . The ditch has been filled . No . 5 Battery is an Ancient monument within the former site of QinetiQ Alverstoke . The rampart is mostly intact and the expense magazines survive . From 1950 the ditch of the Stokes Bay Lines was filled because of complaints from residents of mosquitoes and stagnant water . The section from No . 2 Battery to No . 3 Battery was filled first so that the Stokes Bay Road and promenade could be widened . The final section to be filled was that from No . 3 Battery as far as No . 4 Battery .