Home for two hundred years to one of the Roman Legions stationed in Britannia, modern day Caerleon has been heavily influenced by the huge fortress over which it was built. Initially established to control the Silures tribe, it latter became a depot before being abandoned in favour of coastal defences. The Normans later built a motte and bailey castle nearby.



When the Romans invaded Britain in AD 43, four Legions formed part of the original assault force: the Second Augustian (Legio II Augusta), the Ninth (Legio IX Hispana), the Fourteenth (Legio XIV Germina) and the Twentieth (Legio XX Valeria Victrix). The Second was assigned the task of sweeping down the South of England into Devon and the South West during which they successfully assaulted numerous hillforts (including Maiden Castle and Hod Hill) and by AD 55 they had established their first Legionary fortress at Exeter. Concurrently the Twentieth Legion had pushed into the Midlands and established their base at Usk in South Wales. Despite the Boudica revolt of AD 60, during which the Second Legion was disgraced when it failed to answer the call to rendezvous on Watling Street, trouble elsewhere in the empire saw the withdrawal of the Fourteenth Legion in AD 66 with the Twentieth relocating to their base in Wroxeter. The Second initially moved to Gloucester but by the AD 70s Roman attention was turning back to Wales – in particular the Silures tribe.


South Wales had resisted Roman rule since the initial invasion back in AD 43. The Silures tribe, which occupied an area of South East Wales, was specifically targeted and around AD 75 the Second Legion was ordered to establish a fortress in the heart of their territory from which to defeat and subsequently pacify  the area. Rather than re-use the Legionary base at Usk, which was deemed too far inshore for easy resupply, a new base was established at modern day Caerleon.


The fortress was named Isca by the Romans and was deliberately sited at the mouth of the River Usk where seagoing vessels could resupply the garrison; remains of the large support harbour were discovered in August 2011. Furthermore the River itself and a small tributary, the Afon Lwyd, provided natural defences for the fort. Like other Roman military outposts of the era, be it large or small, it was built to a standard ‘playing card’ configuration based on the marching camps of the earlier army. A single wall, initially timber and later rebuilt in stone, and a V shaped ditch protected the fortress; fairly insubstantial defences designed only to stop a surprise attack as the Legion itself was the fighting machine and ultimately was configured to fight and defeat its enemies in the field. A headquarters building, the Principia, was situated near the centre whilst other facilities needed to sustain a large garrison (Roman Legions alone were circa-5,500 men strong before auxiliaries and camp followers were considered) included extensive barracks, workshops, granaries and a hospital. A bath house, equivalent to a Social Club/Leisure Centre, was also within the fortified parameter. A huge amphitheatre and a parade ground were outside the East Gate.


The Second Legion remained based at Caerleon for at least the next two hundred years. However vexillations were deployed around Britannia and the wider empire. At least seven of the ten Cohorts were employed building Hadrian’s Wall from AD 122 and inscriptions found along the Antonine Wall (built around AD 142) show its presence there whilst a tombstone found at Caerleon also suggests a detachment was deployed to Germany. Throughout Caerleon remained garrisoned however and would have functioned as a regimental depot.


Following the murder of the emperor Commodus in AD 192, a civil war followed during which the British Legions, including the Second, supported Clodius Albinus. In AD 197 they were defeated at Lyons and Septimius Severus won power. Despite suffering heavy losses, the Second Legion avoided disbandment and by AD 208 was sufficiently trusted by Severus to be included as part of his attack on the Caledonians. As the campaign progressed, the Legion was relocated to a new base at Carpow on the Tay. It is likely this would have been the permanent home of the Second, however in AD 211 Serverus died and his sons made peace with the northern tribes surrendering their father’s gains. The Second Legion returned to Caerleon.


By the mid-third century, much of Caerleon seems to have remained unused although a small presence was retained until circa AD 290. As in previous years it is possible that the bulk of the Legion had been detached to fight elsewhere as the Roman Empire slowly destabilised from internal power struggles. By the late third century though both the Roman military deployment and the core threats had changed; large standing armies ready to march to suppress rebellion had been replaced with smaller units stationed at shore forts to counter attacks from pirates and coastal raiders. Around AD 290 the Second Legion, now a much smaller force of just 1,000 men (vice 5,500 of the mid-first century), were re-deployed to the Saxon Shore fort at Richborough. Caerleon itself seems to have remained in occupation although whether this was a military presence is unknown; certainly the focus was now on nearby shore forts at Cardiff and Caerwent although the river crossing at Caerleon would have remained important as a link between the two.


Following the Norman invasion, a motte-and-bailey castle was built at Caerleon possibly by Turstin FitzRolf who was recorded as the owner in the Domesday Book of 1086. Initially timber it was replaced in stone in the thirteenth century utilising the readily available materials from the ruins of the Legionary fortress. It may well have used part of the defensive parameter of the Roman Fort as part of its outer defences. The castle acted as the administrative centre for the Kingdom of Gwent and was attacked and captured by the Welsh in 1171 (by Iorwerth ab Owain), in 1217 (by William Marshal, Earl of Pembroke) and 1405 (by Owain Glyndwr). After this last attack the castle was not repaired and by the sixteenth century was ruinous. Other than the motte and a single thirteenth century tower, little now remains of the castle as the stone was robbed to build the houses of Caerleon.




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Breeze, D.J (2002). Roman Forts in Britain. Shire Archaeology, Oxford.

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Davies, H (2008). Roman Roads in Britain. Shire Archaeology, Oxford.

Goldsworthy, A (2003). The Complete Roman Army. Thames and Hudson, London.

Hobbs, R and Jackson, R (2010). Roman Britain. British Museum Company Ltd, London.

McNab, C (2012). The Roman Army. Osprey, Oxford.

Ordnance Survey, Historic England and RCAHMW (2016). Roman Britain. 1:625,000 Scale. Ordnance Survey, Southampton.

Russell, M and Laycock, S (2010). Un-Roman Britain: Exposing the Myth of Britannia. The History Press, Stroud.

Waite, J (2011). To Rule Britannia. The History Press, Stroud.

What's There?

The Roman remains at Caerleon include foundations of some barracks, the bath house (presented in a dedicated mini-museum by CADW), part of the fort's curtain wall and the amphitheatre. A hugely impressive Roman Legionary Museum is nearby displaying finds from the local area. A Norman motte (to which there is no public access) and bailey tower are also visible.

Roman Caerleon Layout. The layout of the Roman Legionary Fortress is shown above. Like First to Third Century Roman Forts, it was laid out in a playing card shape. Note the Bath House is within the parameter walls unlike smaller forts.

Legio II Augusta. The Second Augustian Legion was a self contained military machine consisting of around 5,500 soldiers many of whom were also qualified craftsmen including stone-masons, carpenters and metal smiths. The Legion was divided into ten Cohorts:

- First Cohort: 800 men split into five double strength Centuries (160 men in each)

- Second to Tenth Cohorts: 480 men in every Cohort with each split into six Centuries (80 men in each).

Barracks. The  excavated foundations of the barracks at Caerleon.

Roman Amphitheatre. The amphitheatre provided entertainment for the thousands of troops garrisoned at Caerleon. Later, in the medieval period, the author Geoffrey of Monmouth suggested that Caerleon was the court of King Arthur and it was thought the ruins of the Roman amphitheatre were the remains of his legendary round table.

Norman Castle. Little remains of the Norman Castle other than this tower and the motte (to which there is no public access).

Getting There

The town is well sign-posted and there is a central car park (pay and display) directly outside the Roman Bath House museum (NP18 1AF). This is an excellent starting point for visitors for either the Roman or Norman remains.

Bath House / Car Park

NP18 1AF

51.6101N 2.9540W

Roman Barracks

NP18 1NF

51.6106N 2.9593W

Roman Amphitheatre

NP18 1AY

51.6081N 2.9569W

Roman Museum

NP18 1AE

51.6100N 2.9554W

Roman Fort Curtain Wall

NP18 1DY

51.6082N 2.9560W

Norman Castle Motte

NP18 1BR

51.6099N 2.9510W

Norman Castle Tower

NP18 1AG

51.6083N 2.9521W