History of Portchester Castle
Portchester Castle stands in a commanding position at the north end of Portsmouth Harbour. The Romans built a huge fort here, which remains the best preserved Roman fort north of the Alps. After the Norman Conquest a castle was built in one corner of the fort, which grew into an impressive royal residence. From 1665 Portchester was frequently used to house foreign prisoners of war, most notably during the wars with France between 1793 and 1815.
The Roman fort
Portchester Castle was begun as a Roman fort, one of the series of coastal forts now known as the Forts of the Saxon Shore. These forts were built over the course of the 3rd century, to meet the threat presented by Saxon pirates who were then raiding the south coast of Roman Britain.
Portchester can probably be identified with Portus Adurni, one of a series of forts along the south and east coasts of Britain recorded in the late Roman military manual, the Notitia Dignitatum.
It seems clear that the fort was founded here because of its commanding position at the head of a huge natural harbour. We have no clear evidence for the date of the original fort, but coins recently found on the site date it to after about 268. Given its evident relationship to the harbour, it may well be that the fort was founded by Marcus Aurelius Carausius, the man appointed by the Emperor Diocletian to command the Roman fleet in the Channel in about AD 285.
Carausius soon fell foul of the tortuous politics of the late Roman empire. When Diocletian’s successor Maximian condemned him to death, Carausius rebelled with the support of the forces under his command, and proclaimed himself emperor in Britain and northern Gaul. Maximian’s deputy, Constantius Chlorus, sent an army against him in AD 293, and in the same year Carausius was assassinated by his deputy, Allectus. Constantius reconquered Britannia for the empire.
The Roman fort here seems to have been fairly constantly occupied up to the end of Roman Britain in the early 5th century. The burial of 27 infants inside the fort suggests that there were substantial numbers of civilians here as well as a military presence. There were timber houses and workshops surrounded by animal pens, cesspits and rubbish heaps within the fort’s walls.
The Norman castle
The Domesday Survey of 1086 states that Portchester comprised three manors before the Norman Conquest. It makes no reference to a fort or castle here, but one of the three manors must have been centred on the Roman fort. This manor was one of the possessions given by William I (reigned 1066–87) to one of his Norman supporters, William Mauduit, with other lands in Portsdown hundred.
By the time Maudit died in about 1100 he had probably laid out the castle’s inner bailey or courtyard in the north-west corner of the vast Roman enclosure. Initially, this probably comprised an outer ditch with a timber palisade, and may have included the first phase of the Norman keep.
After Maudit’s death, the castle and its lands passed to his son, Robert Maudit. But he died in the shipwreck of the ‘White Ship’ off the Norman coast in 1120, and the castle reverted to the Crown. Robert’s daughter, the heiress to Portchester, married another Norman, William Pont de l'Arche, the sheriff of Hampshire. He was an important figure, managing to hold office as sheriff during the reigns of Henry I, his successor, Stephen, and Stephen’s rival for the throne, the Empress Matilda.
The castle’s architectural history in these years is not clear. The first stage of the keep (or great tower) may have been built by Maudit or Pont de l’Arche. At some point in the early to mid-12th century the keep was raised dramatically. Pont de l’Arche also founded an Augustinian priory – a community of priests living together – within the Roman fort’s walls in 1128. This community moved to nearby Southwick in 1150 and its residential buildings were demolished, but their church still stands as Portchester’s parish church. The rest of the fort’s interior was divided into plots and used for farming. Outside the walls, the village of Portchester began to grow up outside the castle's landward gate.
In 1153 Henry of Anjou, son of the Empress Matilda and claimant to the English throne, granted the castle to Henry Maudit, a descendant of the castle’s founder. This is the first clear documentary reference to the castle. But when Henry ascended the throne as Henry II the following year, he took the castle back, one of many baronial castles he confiscated soon after his accession. It then remained in royal ownership until 1632.
Portchester as a prison
Portchester Castle was first used to house captured enemy soldiers in 1665, when England was at war with the Netherlands. The government rented the castle from its owners and housed about 500 Dutch prisoners here. It was used as a prison again during all the major wars of the 18th century, mainly to house French captives. During the War of Austrian Succession (1740–48) Portchester housed around 2,500 prisoners – about a quarter of all the prisoners of war in Britain.
The most important period in Portchester’s history as a prison was that of the French Revolutionary and Napoleonic wars of 1793–1815. Portchester was one of 12 main prisoner-of-war depots in Britain, and housed up to 8,000 prisoners at any one time.
Prisoners of many different nationalities and backgrounds were brought to Portchester in the course of the wars. A group of about 2,000 mainly black and mixed-race prisoners were brought to the castle from the Caribbean in 1796, and remained at Portchester for over a year. Later, a number of prisoners who were among a large group of French captives brought here from the Mediterranean in 1810 transformed one of the rooms in the keep into a theatre. The last prisoners left the castle in May 1814.
Archaeology at Portchester
Between 1961 and 1979 the castle was the scene of major archaeological excavations directed by Professor Barry Cunliffe. These have transformed our understanding of its long history.
The excavations produced thousands of finds, ranging from prehistoric times to the 19th century. Geophysical survey – which collects information on hidden features without the need for excavation – revealed the presence of many buried features, including the sites of the timber buildings that housed the prisoners of war in the late 18th and early 19th centuries.