Southsea Castle: A Tudor Artillery Fort at Portsmouth
Site at a Glance
- Rating
- 4.5
- Popularity
- Medium
- Country
- United Kingdom
- Primary era
- Modern
- External website
- Open
- Eras represented
- Early Modern, Modern
- Civilizations
- British, English
- Site type
- Military
- Remains
- Castle
On this page20 sections
History
Southsea Castle is a Tudor artillery fort in the United Kingdom, built on the southern end of Portsea Island at Portsmouth to defend the eastern approach to the naval base and the deep-water channel through the Solent. Also known as Chaderton Castle, South Castle, and Portsea Castle, it formed part of Henry VIII’s coastal defence programme, created amid worsening tensions with France and the Holy Roman Empire. Construction probably began in 1544, although 1543 has also been proposed, and the work was complete by October 1544.
The Henrician foundation
Henry VIII, who ruled England from 1509 to 1547, directed a major programme of coastal fortification after his break with the papacy and the deterioration of relations with France and the Holy Roman Empire. These royal “devices,” meaning programmes or instructions for defending the realm, produced a network of artillery forts often called the Henrician castles. Southsea Castle protected Portsmouth and the Solent within this wider defensive system.
Sir Anthony Knyvett, Governor of Portsmouth, directed the work with assistance from Richard Cawarden, Dean of Chichester, and John Chatterton, captain of the Portsmouth garrison. Thomas Bertie was the master mason, but the designer is uncertain. Knyvett described the fort as being “of his Majesty’s own device,” suggesting that Henry VIII may have played a personal part in its conception. The construction cost at least £3,100, including £1,300 obtained from the Dissolution of the Monasteries. Chalk, stone, and timber came from the neighbouring Isle of Wight.
Two brass saker guns, a type of cannon, were mounted at the unfinished fort in July 1544. Once complete, the garrison consisted of a captain, eight soldiers, twelve gunners, and a porter. Its armament comprised seven brass artillery pieces and eight iron guns.
The Battle of the Solent and Tudor strengthening
Southsea Castle was drawn into the crisis of July 1545, when a French fleet of about 200 ships entered the Solent during the Battle of the Solent. The English flagship Mary Rose sank during the campaign. Henry VIII was at Portsmouth, and the Cowdray engraving of the battle shows him visiting Southsea Castle. The immediate danger ended when the French fleet moved along the coast on 25 July, but the king ordered further improvements to guard against an infantry assault. These included stone flankers, which allowed defenders to fire along the walls, and timber caponiers, or protected passages extending into the moat.
Edward VI spent a night at the castle in 1552 while inspecting Portsmouth’s defences. By the early seventeenth century, however, the fort had received little attention. It was described as poorly prepared, with no guns mounted along its walls and no stored gunpowder. A serious fire in March 1626 destroyed the interior of the keep. Repairs were completed in 1635 using 210 loads of timber from the New Forest, but another fire damaged the lodgings and storerooms in 1640.
Civil War capture and the Restoration rebuilding
At the beginning of the English Civil War in 1642, Southsea Castle was held for the Royalists by Captain Challoner. The English Civil War was the conflict between supporters of the monarchy and supporters of Parliament. The castle had a small garrison of about eleven or twelve men and fourteen guns. On 5 September, Colonel Richard Norton attacked with 400 infantry and two troops of cavalry. Because the defenders had aimed their guns inland, Parliament’s forces approached from the seaward side, stormed the moat, and compelled the garrison to surrender without loss of life. Portsmouth then surrendered, and Parliament installed a substantial garrison at the castle.
During the Interregnum, the period between the execution of Charles I and the restoration of the monarchy, and during the early Restoration, the castle served mainly as a prison. Fears of a Dutch attack led Charles II to commission Sir Bernard de Gomme to improve Portsmouth’s defences in 1665. Work at Southsea began in the 1680s. The rebuilding added an earthwork glacis, a sloping bank outside the fort intended to expose attackers to defensive fire, together with a new gate, four projecting turrets, and a redesigned keep. A large stone plaque on the gatehouse bears Charles II’s coat of arms and the date 1683.
The castle also played a part in the political crisis of 1688, when opposition to James II led to the transfer of power known as the Glorious Revolution. On 18 December, George Legge, Baron Dartmouth, pressured James FitzJames, Duke of Berwick, to transfer control of the castle to the Protestant Captain Carter. Portsmouth surrendered to the Revolution two days later.
Fire, erosion, and Napoleonic reconstruction
In August 1759, cooking sparks ignited gunpowder stored by the 72nd Regiment of Foot. The resulting explosion badly damaged the east side of the castle and killed seventeen men, women, and children. The Firebarn, a new powder store, was probably built outside the north side as a consequence. By the later eighteenth century the fort was again in poor condition, and coastal erosion had destroyed most of the eighteenth-century grand battery by the end of the century.
Possible invasion from France prompted urgent preparations in 1797. Only eight 32-pounder guns and five 6-pounder guns were available, and they were in poor condition. During the Napoleonic Wars, a larger reconstruction began in 1813 under Major-General Benjamin Fisher. The north side was extended by up to 30 feet, the keep and interior bailey were redesigned, the moat was rebuilt, and a counterscarp gallery, a defended structure along the outer edge of a ditch, was added. Most of the work was finished in 1814, with the remaining elements completed by 1816.
Victorian artillery and the changing coastline
Southsea Castle became a military prison from 1844 to 1850, holding 150 military offenders under the supervision of a Royal Artillery sergeant. After the prison closed, seven 8-inch guns were placed in brick emplacements along the walls, and two auxiliary earthwork batteries were built beside the castle.
Rifled cannon and ironclad warships altered coastal warfare in the nineteenth century. Between 1863 and 1869, new east and west batteries with underground magazines were built as part of a 17-acre defensive complex enclosed by a wall. The older castle then served mainly for range and direction finding rather than as the principal gun position. By 1886, the wider site mounted twenty-five rifled muzzle-loading guns. Five 6-pounder quick-firing guns and searchlights were added in the 1890s, and the east battery was converted for breech-loading guns between 1899 and 1901.
The government took possession of Southsea Common in 1785 to keep the ground around the castle open for its guns. Convicts began filling and levelling the marshland in 1831. Urban development, private housing, the railway, and Southsea’s growth as a resort made live firing increasingly difficult. Portsmouth City Council bought the Common in 1922 and converted it into a park.
Twentieth-century defence and museum use
At the beginning of the twentieth century, Southsea Castle formed part of the Fortress Portsmouth defence plan. During the First World War, Royal Garrison Artillery units manned the site, including the Hampshire Royal Garrison Artillery Territorials. After the original units went to France, Hampshire Royal Garrison Artillery Volunteers took their place. A 3-inch anti-aircraft gun was installed against Zeppelin raids. The west battery was disarmed in 1927, although the castle continued in military use for a time.
During the Second World War, the castle served as headquarters of Portsmouth Fixed Defences. The Hampshire Heavy Regiment, Royal Artillery, regular coastal artillery, and Home Guard units occupied the site. Its east battery mounted two 9.2-inch guns, and barrage balloons formed part of its protection. At least two incendiary bombs struck the castle, but caused little damage.
On 23 June 1940, after the fall of France, the castle was ordered to prepare to fire on French naval vessels in Portsmouth. The destroyer Léopard aimed its guns at the castle, but neither side fired. On 3 July, British forces seized the French vessels under Operation Grasp, the British takeover of French naval ships in British ports to prevent their possible control by Germany, bringing the confrontation to an end.
After the fort became obsolete, Portsmouth City Council bought it for £35,000 in 1960. The council removed many later military additions, restored the castle toward its pre-1850 appearance, landscaped the surrounding area, and conducted archaeological surveys. The west and east batteries were partly demolished during the 1960s, and the castle opened as a museum in 1967. A major council cleaning programme preceded its reopening in 2011. Southsea Castle remains a council-operated public museum and is protected under United Kingdom law as a Scheduled Ancient Monument.
Remains
Southsea Castle’s surviving core is a stone fort arranged around a square central keep. Rectangular gun platforms occupy the east and west sides, while angled projecting works form the seaward southern and landward northern sides. The plan represents an early and imperfect English adoption of the continental trace italienne, an angular fortification style designed to resist cannon fire. Its projecting bastions enabled defenders to cover the walls with flanking fire. A dry moat surrounded the castle, and the keep itself was enclosed by a square moat set diagonally in relation to it.
Keep, walls, and entrances
Sixteenth-century fort
The original fort was built of stone around the square keep, with gun platforms and angular outer works integrated into the defensive plan. The southern and northern walls formed bastions, while the dry moat added a further obstacle around the enclosure. These features reflect the transition from older semicircular bastions, whose sides could not be fully covered by flanking fire, to more angular arrangements suited to artillery warfare.
Restoration-era rebuilding
The rebuilding of the 1680s altered the entrance and central structures. An earthwork glacis was formed outside the fort, a new gate was constructed, four projecting turrets were added, and the keep was redesigned. The gatehouse still carries the large stone plaque displaying Charles II’s coat of arms and the date 1683.
Napoleonic reconstruction
The reconstruction of 1813 to 1816 extended the fort northward by up to 30 feet. The keep and interior bailey, the enclosed area around the central tower, were rebuilt in brick. The moat was reconstructed, and a counterscarp gallery was added around its edge, providing a defended structure along the outer boundary of the ditch.
Lighthouse and harbour navigation
Western lighthouse
A lighthouse was built on the western gun platform in 1828 on Admiralty commission. Its height was increased in 1854, bringing the light to 34 feet above its base on top of the walls. It originally used a sperm-oil lamp behind a fixed dioptric lens, a lens system that concentrates light into a navigational beam. Red and white sectors guided vessels through safe water between Horse Sand and Spit Sand; the colours changed to red and green in 1854. The lighthouse keeper lived within the castle.
Later lighthouse equipment
The lighthouse operated continuously until 2017, when a new structure replaced it because the approaches to Portsmouth Harbour had changed for the arrival of Queen Elizabeth-class aircraft carriers. The original dioptric lens, which was later replaced in service, is displayed inside the castle.
Later batteries and artillery
East and west batteries
The nineteenth-century defensive complex placed additional batteries on the east and west sides, with underground magazines and a surrounding defensive wall enclosing 17 acres. The older castle became a position for range and direction finding. By 1886, the site contained twenty-five rifled muzzle-loading guns. Five 6-pounder quick-firing guns and searchlights were added later, while the east battery was adapted for breech-loading weapons between 1899 and 1901.
First World War armament
During the First World War, the east battery held two BL 6-inch Mark VII guns and two BL 9.2-inch Mark X guns. The west battery contained three 12-pounder guns and one 4.7-inch quick-firing gun. A QF 3-inch 20 cwt anti-aircraft gun was also installed. In the Second World War, the east battery retained two 9.2-inch BL Mark X guns, while the site’s surviving fabric sustained only slight damage from at least two incendiary bombs.
Surviving cannon
The castle and its grounds contain a collection of cannon illustrating later developments in artillery. A 68-pounder and an RML 9-inch 12-ton gun stand outside. Inside are a 24-pounder from HMS Royal George, an RML 9-pounder 8 cwt gun, and two hexagonally rifled Whitworth 3-pounder breech-loaders dating from 1876. RML means rifled muzzle-loading, BL means breech-loading, QF means quick-firing, and cwt means hundredweight.
Surviving nineteenth-century complex
The post-1960 restoration removed many features added after 1850 and sought to recover the castle’s earlier appearance. The east and west batteries were partly demolished during the 1960s, while archaeological surveys accompanied the work. The remaining castle, its altered walls and moats, the lighthouse, surviving gun positions, and the retained artillery collection together represent successive phases of coastal defence from the Tudor period through the age of modern naval warfare.
