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Military History of Hilsea Lines

Introduction
The history of Hilsea Lines very much reflects the development of Portsmouth as a military base. In 1544, during Henry VIII’s reign, the first defences were built just north of Ports Creek to protect the naval interests from an inland attack. Not until 1757 were defensive lines established to the south of the creek where they remained largely unaltered for over 100 years. The existing lines replaced them when the renewed threat of a French invasion prompted the need for stronger defences. Construction was started in 1858, completed in 1871 and cost £260,000. The expected invasion did not materialise and the Lines were never used in battle.

The Casemates
A casemate is a bombproof vaulted building. These were designed to provide gun emplacements which afforded protection to the guns and their crews. The gun positions were arranged along the front of the casemate in a long room known as the gun gallery.
Behind the gun positions were rooms, separated by curved corrugated iron blast shields, each of which provided living accommodation for five men. The guns in the casemates provided cross-fire to prevent the enemy crossing the creek and to provide low profile fire along the front of the lines. A typical layout consisted of 2 gun galleries, various armaments stores, 9 accommodation rooms, a cook house and a wash room.      
                    
Moncrieff Disappearing Gun
(an addition to the Lines in 1875)
A forerunner of the turret gun demonstrating the technical brilliance of the Victorian engineers. The 7 ton gun was forced down into the gun pit for re-loading by the recoil after the gun fired. A counter balance then raised the gun after loading. The 6 gun pits had surrounding walls made of concrete cast to look like stone. Despite the walls great thickness the concrete has now deteriorated as the technique of steel reinforcement was not developed until after their construction.

Royal Artillery Badge
Troops from the Royal Artillery were responsible for manning the lines from 1860 and their badge can still be seen on the rainwater  hoppers at the back of the casemates. Their latin motto ‘Ubique Quo Fas Et Gloria Ducunt’ is translated as ‘Everywhere and wherever right and glory lead’.

Expense Magazines
Small buildings situated along the top of the ramparts to be utilised during battle for storing ammunition for the nearby gun positions. These lines originally had 34 expense magazines and were built to be bomb resistant with arched ceilings and a thick covering of chalk and earth.

40 Pounder Rifled Muzzle Loader Gun
Set on travelling carriages to enable them to be mobile, there were 8 of these at Hilsea during the 1890s and were used to supplement the similarly designed 32 pounder guns of which there were over 150. They were dragged up the gun ramps by manpower to the top of the ramparts, then positioned behind the earth parapets ready for action. Due to their mobility these guns provided some degree of flexibility to assist the fixed defensive positions of the casemates and the gun pits. When complete Hilsea Lines extended for 2.5km along the whole northern side of Portsea Island and largely remain today. The original gateway on London Road was taken down to allow for road widening in 1919. In 1940 a section was removed at Peronne Road to create an emergency access onto Portsea Island, should Portsbridge be destroyed by German bombers. However, the construction of Portsmouth’s airfield at the eastern end of Hilsea Lines resulted in the largest part of the Lines being demolished in 1932. This is now occupied by the Anchorage Park development.

Associated documents:

• Hilsea Lines History Leaflet  (0.76 MB)

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