Southsea Castle was built as part of the second phase of Henry VIII’s vast coastal defence programme. Significantly different from his earlier fortifications, it was configured with angled bastions and artillery that could cover all approaches. It was substantially rebuilt in the early nineteenth century and continued to play an important role in coastal defence until World War II.



A Tudor Device


In 1536 Henry VIII declared himself Supreme Head of the Church of England thus breaking the link with Rome. His motivation was to secure a divorce from his first wife, Catherine of Aragon, which had been refused by the Pope. He subsequently granted himself the divorce and also commenced a wholesale confiscation of the vast wealth amassed by the church prompting international condemnation. Despite this, England was safe from any intervention as Europe’s strongest powers – France and Spain – were locked in conflict with each other. However, in 1538 the two nations signed a ten-year truce prompting fears one or both could invade England. To mitigate the threat a Device (Act) for the protection of the realm initiated a vast coastal defence programme on a scale unseen since the Romans. Government officials surveyed poorly defended areas along the coast with the Solent being regarded as particularly vulnerable due to the access it afforded to the rich town of Southampton as well as control of the Isle of Wight. Construction of Calshot Castle, guarding the waterway to Southampton, began in Spring 1539 as did fortifications at East and West Cowes. Hurst Castle was added in 1541 controlling the western access to the Solent.


The invasion fears of 1538/9 passed quickly as France and Spain resumed their hostilities. By 1544 Henry himself had joined with Charles V of Spain and invaded France in a campaign that ended in the capture of Boulogne in September 1544. But shortly after, France and Spain once again made peace and the former looked to invade England. Further fortifications were commissioned to protect the Solent at Sandown, Yarmouth and Southsea.


A New Design


Henry’s forts of the 1539 programme had been predominantly concentric in design with rounded bastions. By contrast the new forts were influenced by the King’s exposure to the latest military concepts during his Boulogne campaign and were constructed with angular bastions. Yarmouth was the first example of this - there the roughly square castle had additional protection from an arrowhead bastion on the landward side. Southsea took the design one step further; both the north and south walls were angular allowing covering fire along their length. The castle also had a square, central Keep and a dry moat which was protected by gun openings in the lower section of curtain wall. Two rectangular gun platforms were built on the east and west sides.


French Attack


The expected French attack occurred in July 1545 when their Fleet arrived in the Solent. They landed soldiers on the Isle of Wight with fighting around the unfinished structure of Sandown Castle. The French did not get in range of the guns of Southsea Castle but the King watched from the top of the Keep as the English Fleet sailed to intercept and he witnessed the capsize of the Mary Rose.


The Armada


The French attack was not repeated but the castle remained garrisoned throughout the rest of the Tudor era. The dry moat was enlarged in 1577 and it can be presumed the castle was placed on high alert as the Spanish Armada approached in 1588. Thereafter the castle went into a period of decline; when James I (VI of Scotland) came to the throne in 1603, he sought peace with Spain resulting in the coastal defences being starved of funding. The situation was compounded in 1627 when the Keep was gutted by fire and was not repaired until 1635.


The Civil War


At the outbreak of the Civil War in 1642, Portsmouth (including Southsea Castle) was under the control of its Governor, Lord George Goring. In the months preceding the war he had fluctuated between both Royalist and Parliamentary sides but ultimately declared for the King in August 1642. Parliamentary forces converged on Portsmouth with Colonel Richard Norton - a resident of nearby Southwick - tasked with taking Southsea Castle. On 3 September 1642 he launched a night assault with two troops of cavalry and 400 infantry. The castle, under the Command of Captain Chaloner, was well armed but had an inadequate garrison of just 12 men and was further hampered by the fact Chaloner was intoxicated! The assault quickly overwhelmed the small garrison and the castle's fall, coupled with the Parliamentary capture of Gosport, left Portsmouth untenable for the Royalists. The castle played no further part in the Civil War.


The Dutch Wars


Southsea Castle was upgraded in 1665 under the direction of Sir Bernard de Gomme. At this time Britain was engaged in a protracted struggle for maritime supremacy with Holland. Wars had been fought between 1651 and 1654 over the Navigation Acts; legislation that imposed limits on third party carriers which impacted upon the Dutch. War broke out again in 1665 and this prompted the upgrades to Southsea consisting of a new 30 gun platform external to the Tudor fortification and an earth bank (a glacis) surrounding the curtain wall to protect it from artillery fire.


French Wars


After the Dutch Wars, Southsea Castle was neglected although it remained garrisoned. In 1759 the castle was devastated by a gunpowder explosion which killed 17 people. No funding was allocated to enable repairs and accordingly it became dilapidated. The de Gomme gun battery was also destroyed by coastal erosion at this time. By 1785 the castle was considered to be beyond economical repair when a report by the Master-General of Ordnance - Charles Lennox, Duke of Richmond - recommended it should be demolished and replaced with a new square redoubt. Ironically Lennox had been the commander of the 72nd Regiment of Foot whose gunpowder had caused the explosion in the first place and had been camped on Southsea Common when the incident occurred. Regardless, financial difficulties frustrated the demolition plan and, when war broke out with France in 1793, urgent work was undertaken on the castle to restore it to readiness.


Napoleonic Wars


In 1812 Major-General Benjamin Fisher was appointed to overhaul the defences of Portsmouth and commenced major upgrades to Southsea Castle. The north curtain wall was demolished and rebuilt with a 9 metres extension facilitating enhanced gun platforms and additional barracks.  The top of the Keep was also modified with the Tudor watchtower removed and its crenellations flatted to enable four additional gun batteries to be installed. The south curtain wall was also demolished and replaced with a curved bastion for the seaward facing battery. The moat was also significantly modified with a counter-scarp gallery built into the outer face and connected to the castle via a caponier. The modifications were completed by 1816 by which time the threat from France had diminished following the final defeat of Napoleon at the Battle of Waterloo (1815).


Further Upgrades


In 1844 the modified barracks added during the earlier upgrades were converted into a military prison. This role was short-lived though as in 1850 the prisoners were relocated to a dedicated facility in Gosport. This was timely for in 1852 Napoleon III became Emperor of France and commenced an arms race with Britain. In particular the French development of the first Ironclad warship ('La Gloire'; the Glory) – an armoured vessel outclassed anything in the Royal Navy and threatened Britain’s maritime superiority – prompted a review of coastal defence. The armament of the castle itself was upgraded first and in 1856 auxiliary batteries were added either side of the former Tudor fort. As the situation with France deteriorated further, a Royal Commission was initiated to report on further new fortifications which led to an entire network of new forts protecting Portsmouth. Southsea also received upgrades under this scheme – between 1863 and 1869 the auxiliary batteries flanking the castle were upgraded and the adjacent Common converted into a military zone enclosed with a curtain wall. Later in the nineteenth century additional weaponry – including Quick Firing guns aimed at countering the threat from fast motor torpedo boats – was installed on the external batteries.


World Wars


Southsea Castle continued to perform a coastal defence role during both World Wars. In the First World War searchlights were installed and a continuous watch made but it saw no action. By contrast during the Second World War the castle was bombed with incendiaries on several occasions. It also came close to having a fire-fight with French Naval forces in June 1940 when, with the fall of France, the British Government issued a directive that they should surrender to the Royal Navy or be sunk. This crisis was only averted when the French ships were seized by boarding parties on 2 July 1940.


After the War


With the advent of air power, coastal defence sites across the country were decommissioned in 1956. Southsea Castle was sold to Portsmouth City Council who restored the castle and opened it as a museum.





Allen, R (1976). English Castles. Batsford, London.

Brroks, S (1996). Southsea Castle. Portsmouth City Council.

Colvin, H.M (1986). The History of the King's Works, Vol 4. HMSO, London.

Harrington, P (2007). The Castles of Henry VIII. Osprey Publishing, Oxford.

Johnson, P (2006). Castles from the Air: An Aerial Portrait of Britain’s Finest Castles. Bloomsbury, London.

King, C.D.J (1983). Castellarium anglicanum: an index and bibliography of the castles in England, Wales and the Islands.  Kraus International Publications.

Morley, B.M (1976). Henry VIII and the development of coastal defence. HMSO, Worcester.

Saunders, A.D (1966). Coastal Defences since the introduction of artillery.

What's There?

Southsea Castle was one of the final Device forts built by Henry VIII and constructed to a significantly different design from his earlier castles. It was extensively rebuilt in the nineteenth century.

Southsea Castle Context. The castle guarded the deep water entrance into Portsmouth Harbour as well as the Eastern Solent.

Southsea Castle. The castle had a clear view across the Solent although the range of its guns was limited to covering the channel into Portsmouth Harbour.

Southsea Castle Layout (1816). The Henrician castle was configured with two rectangular gun platforms at either end whilst whilst the north and south curtain walls had triangular bastions extending from them. The modifications made between 1812 and 1816 remodelled the south bastion into a semi-circular configuration and rebuilt the north one adding a 9 metres extension. A counter-scarp gallery was added into the outer face of the moat accessed via the caponier.

Southsea Castle. The castle has been heavily modified over the years. The brick built additions are the most obvious but the angled bastion, Keep and ditch were all converted during the nineteenth century.

Square Keep. Unlike the 1539 fortifications, which had circular Keeps, the design at Southsea was a simple square. It originally had a watch-tower and crenellations but these were removed in 1812.

Counterscarp Galley. The modifications of 1812 to 1816 added a counter-scarp gallery to the outer edge of the moat allowing the defenders to fire upon attackers. It was accessed via the caponier (seen to the right in the picture above).

64 Pounder Gun. A 64-pounder Rifled Muzzle Loading (RML) gun dating from 1872. The brick rampart was used as it was thought less likely to splinter than stone when hit by a missile.

Castle Entrance. The coat of arms over the entrance belongs to Charles II. During his reign major modifications were made by Sir Bernard de Gomme.

Gun Batteries. The gun batteries seen external to the castle were built following the recommendations of the 1859/60 Royal Commission. Originally much of Southsea Common formed part of a military zone enclosed by a curtain wall.

Getting There

Southsea Castle is located on the waterfront and sign-posted as part of the Waterfront Tourist attractions. There are extensive parking facilities (on-road and a public car park) in the immediate vicinity. The D-Day museum is next door.

Car Parking


50.779727N 1.090090W

Southsea Castle


50.778181N 1.088818W