Little is known about Portchester’s pre-Roman history. Archaeological excavations have been inconclusive and early documentary evidence is hard to decipher. Early chronicles refer to a place known as Caer Peris. A 1784 publication records that: “It was once a town of note, then called Caer-Peris … it was built by Gurgunstus, son of Beline, who lived three hundred and seventy-five years before Christ”.
In AD 43, it lay on the western fringes of the tribal kingdom of the Regnenses. Their king, Togidubnus, was a pragmatic leader who readily embraced the advantages of working with Rome, rather than trying to fight it. He recast himself as Tiberius Claudius Cogidumnus (sources use a variety of different spellings), took the title Legatus Augustus and quickly gained the wealth, status and influence to build an opulent palace at Fishbourne, near Chichester in West Sussex.
Portchester’s time was to arrive 250 years later as barbarian raiders operating from bases on the eastern shores of the North Sea began terrorising the coastlines on both sides of the English Channel. In AD 285, the Roman emperor Diocletian appointed a former Belgian sea captain named Carausius to prevent the attacks.
Carausius, a “poacher turned gamekeeper”, soon reverted to form. Rather than tackle the raiders on their way to attack Britain’s “Saxon Shore”, as Rome had ordered, he preferred to pounce as they were returning laden with booty he could seize for himself. Soon, he had amassed enough wealth and power to restyle himself Marcus Aurelius Carausius and declare himself, the following year, Emperor of Britannia. Coins found at Portchester bearing his image and dated between AD 285 and 290 are accepted as firm evidence the Roman fort was built during this period.
Known then as Portus Adurni, Portchester was among the largest of the so-called “Saxon Shore” forts built at this time. Today, it is it is recognised internationally as the best-preserved of any Roman fortification built north of the Alps.
The Roman walls enclose an area roughly 3.64 hectares (9 acres) in area. They stand some 6.1 m (20 feet) high, with an average thickness of 3 m (10 feet). The perimeter was built in sections 36.5 m (120 feet) long, each built up in horizontal layers of flints spread with mortar to bond the stones together. Larger flints were used to dress the outer faces and limestone slabs or fired tiles were added for reinforcement and to keep courses level. Wooden scaffolding and shuttering helped support each new layer while the mortar dried.
D-shaped watchtowers were built at intervals around the perimeter walls as platforms for ballistaria, early catapult-based artillery capable of hurling heavy stones some 50 metres. Ditches were dug around the perimeter walls to trap attackers within the ballistaria’s killing zone.
The watchtowers still remain today but other original Roman features survive less well. The inner facing of the perimeter walls was used to construct new buildings during the Middle Ages and the imposing Landgate and Watergate entrances are later modifications built onto the original Roman foundations.
Saxon Occupation and Norman Invasion
Coins and pottery found at Portchester suggest the fort continued to be occupied from the collapse of the Roman Empire through to the Norman conquest of 1066, when it passed into the hands of William Maudit, a close associate of William the Conqueror. Maudit is believed to have established the layout of the inner bailey. His death around 1100 saw the castle pass to his son, Robert, then via the marriage of Robert’s daughter, to William Pont de l’Arche, Sheriff of Hampshire and a powerful individual in the court of Henry I.
William built the lower level of Porchester Castle’s keep, which originally rose to only half its modern-day height. He also founded an Augustinian priory and built the Parish Church of St Mary within the Roman walls. Two later phases of building before 1320 added three new storeys to the keep and raised it to its present height of just over 30 m (100 ft).
Royal Residence
By 1154, Portchester Castle’s ownership had passed to the newly-crowned Henry II who used it frequently to travel to and from the Continent where his territories extended from Flanders to the Pyrenees. Royal Exchequer records dating from his reign note repairs to a royal residence believed to have stood inside the inner bailey, the use of the castle as a prison and as a stronghold for Henry’s treasury, and various improvements carried out to the Castle’s defences.
The Castle fared less well under Henry’s son, Richard I, who granted Portsmouth its first Royal Charter in 1194 but spent most of his 10-year reign abroad. Richard’s successor, King John, used Portchester mainly to indulge his passion for hunting in the neighbouring Forest of Bere.
Following the French invasion of England in 1216, culminating in the signing of the Magna Carta, Portchester again became a favoured royal port of entry and embarkation. Henry III (r 1216-72), Edward I (r 1272-1307), and Edward II (r 1307-27) all carried out documented improvements. Edward III (r 1327-77) prepared at Portchester for the campaign leading to victory at the Battle of Crécy. Richard II (r 1377-99) improved the royal apartments inside the inner bailey and adapted the keep and Landgate.
Later royal visitations gradually became less frequent, if no less grand. Portchester was chosen in 1445 as the landing place for Margaret of Anjou, Henry VI’s French bride-to-be. Henry VIII visited the Castle in October 1535 in the company of Anne Boleyn and, in 1583, the fortifications were overhauled in anticipation of the Spanish Armada two years later. Elizabeth I (r 1558-1603) held court at Porchester during the final year of her reign and is believed to have ordered further improvements.
However, London was becoming the centre of economic and political life and Portsmouth, at the mouth of the Harbour, had begun its ascent to become the nation’s most important military headquarters and dockyard. Portchester Castle’s time as a royal residence had all but run its course.
Prison
The end of the Castle’s royal status was confirmed in 1632 when Charles I (r 1625-49) sold it to a local landowner. It served briefly as a base for Parliamentarian mounted infantry during the first English Civil War, when Portsmouth was in Royalist hands, then in 1665 held prisoners taken in the course of the Second Dutch War.
It continued to perform a similar function for most of the next century-and-a-half, leased by the Crown to house prisoners of war. Overcrowding soon became a major issue, the castle’s population rising from 1,100 to 2,500 between 1746 and late 1747 alone. By 1760, the castle housed 235 militia guarding 3,200 prisoners. By 1800, along with extra floors built into the keep, 13 new timber buildings had been constructed within the Roman walls, each designed to house 500 men.
But for a brief period as an ordnance depot, Portchester Castle retained its role as a prisoner-of-war camp until 1814. It then spent five years as a hospital and prison for deserters before being returned to the original landowner’s family in 1819.
Just over a century later, the family put the castle—by then all but a derelict ruin—into the care of the Office of Works, who took on a workforce mainly of Welsh miners made jobless in the depression of the 1920s to clear and partly restore the site. The Castle was eventually made over to English Heritage, who remain responsible for its upkeep, in 1984.
Did You Know?
- The sockets left by the wooden scaffolding used to erect the Roman walls of Portchester Castle are still visible today, as are the vertical joints between some of the individual sections. Each 36.5 m (120 ft) section corresponded in length to a Roman measurement known as an actus.
- Evidence of King John’s passion for hunting includes bones found at Portchester of several species of birds of prey used in falconry. The Forest of Bere originally extended northwards from the coastal fringes between (approximately) the modern-day towns of Havant in the East and Fareham in the West. Much of the timber used later for the dockyard in Portsmouth would have been sourced there.
- The priory built inside the Roman walls by William Pont de l’Arche soon moved four miles away to Southwick but St Mary’s church still thrives as one of the most outstanding 12th century chuches still in active use. Its churchyard has 29 Imperial War Graves Commission memorials and contains the graves of leading maritime artist W L Wylie RA and Thomas Goble RN, a master mariner on HMS Victory co-opted by Admiral Lord Nelson as his secretary at the Battle of Trafalgar.