Caerleon – Roman Legionary Fort


   Caerleon Legion Fort, called Isca in Roman times, was built around 75 AD. Its construction was related with the campaigns of the Britain’s governor, Julius Frontinus against the Celtic tribe of Silures, who occupied the lands of south-east Wales. This tribe resisted the Roman invasion for more than thirty years, inflicting several major defeats on the invaders. Frontinus changed strategy by deciding to build a fort deep in enemy territory, where it would be possible to defend itself effectively and at the same time pacify the natives. The place of the fortress was chosen because of its location on the gently rising terrain adjacent to the Usk River, which was accessible to sea-going vessels, and near the routes between Wroxeter, Gloucester and Carmarthen. Thanks to this, the ability to easily send supplies to Isca was secured. The fort was the seat of II Augusa legion, a unit of about 5,500 men, along with accompanying staff and Roman residents. During this period, the legion was divided into cohorts, the first of which consisted of 800 legionaries, and the remaining four of 480, each divided into six centuries.
   The fortifications were used by II Augusta legionnaires until about 300 AD. Around 122, some of the fort’s buildings could be depopulated due to the construction of the great wall by Emperor Hadrian in northern Britain. For this reason, numerous craftsmen and bricklayers were drawn from all over the province, as well as troops to protect them. Roman tomb inscriptions found at Hadrian’s Wall confirm that there were also legionaries from the cohorts of II Augusta. In turn, when the emperor Commodus was murdered in 192 and the civil war broke out, the II Augusta legion went to Gaul to support the pretender Clodius Albinus, governor of Britain, proclaimed Roman emperor in 196–197. Finally, he suffered a defeat along with II Augusta at the Battle of Lugdunum.
   At the beginning of the third century, after normalizing the political situation under the rule of Emperor Septimius Severus, Caerleon still served as the main seat of the II Augusta legion, although it is known that it was sent north to stabilize the Caledonian border. There were probably plans to permanently move the legion there, but eventually in 211-212 Karakalla made peace, and Isca was thoroughly renovated. The next involvement of the Caerleon legion was caused by internal fighting after the assassination of the emperors Alexander Severus in 235 and Gordian III in 244. During the absence of the army, the buildings, including baths and the amphitheater, were maintained by local staff and residents, however, the decayed barracks were renovated in 274 -275 during the more peaceful reign of Aurelian.
   The fort ended in 287-293 when the uzurpator Carausius proclaimed himself Roman emperor, supported by troops on the island. Expecting the invasion of Britain by the legitimate rulers of Diocletian and Constantius, he began preparations for defense. Among them, part of the fort’s buildings were demolished, probably to be used elsewhere. It was later partly inhabited, although it is not known whether by civilians or military units.
   In the Middle Ages, Caerleon was one of the administrative centers of the Kingdom of Gwent. In the Roman fort a parish church was built, and a Norman motte and bailey castle. During the Welsh-Norman battles, in 1171 Iorwerth ab Owain and his two sons destroyed the town and burnt the castle. In 1217, both the castle and the settlement were occupied by Wilhelm Marshall, who rebuilt the feudal stronghold. The remains of many ancient Roman buildings have probably been preserved so far to some extent, but were then probably destroyed in order to obtain building materials.


   Isca was situated on a slight elevation in a wide bend of the Usk River, which provided protection from the south, and to a large extent from the west and east. The fort covered an area of ​​50 acres, and its earliest fortifications consisted of peat-clay ramparts topped with timber fortifications. The fortifications were built on a rectangular plan with an entrance gate in the middle of each side. The fortifications were strengthened by twin wooden towers flanking all the gates and single wooden towers spaced at equal intervals in the perimeter of the fortress walls. The outer defense zone was a ditch with a V-shaped cross section, 8 meters wide and 2.5 meters deep, surrounding the entire fort. The rampart with vertical walls reinforced with oak piles was 5.5 meters wide and up to 3 meters high. There was a wall-walk on the inside of the rampart, allowing legionnaires to quickly access each endangered fragment.
   At the beginning of the 2nd century AD the fortifications were rebuilt into stone ones. The outer part of the embankment received a stone wall 1.5 meters thick, and the gates were reinforced by twin stone towers. Also the remaining wooden towers were replaced by a series of stone, four-sided towers spaced at intervals of 43 meters. Each tower had two floors, the lower one was a basement inserted into the earth rampart and served only as a warehouse. The upper floor was accessible through the door in the rear wall of the tower and connected to the defensive wall-walk in the crown of fortifications.

   The internal layout of the fortress was in line with the standard plan of the legionary fort: the road via principalis ran from east to west, and via praetoria from north to south. In addition, there was a network of other smaller, perpendicular and parallel roads connecting different areas of the fort. The earliest buildings were probably built of wood, later replaced with stone. In the center was the headquarter, behind which the legate’s residence was located, and opposite, along the via principalis, a row of buildings of higher commanders. On both sides of the headquarter there were workshops intended for industrial iron processing, also occupied by legionary craftsmen, bricklayers, blacksmiths, tanners, carpenters, shoemakers, etc.
   Legionary barracks adjoined the northern and southern sides of the fort and in the middle of the western and eastern curtain. There must have been 60 of them, because the single building housed a centurion (80 men), with ten groups of eight men sharing two rooms (6 centurions equals 480 men in cohort). The smaller of the two rooms was used as a warehouse, the larger room served as a bedroom. At the end of each block of barracks was the centurion’s residence, which also included flats for junior officers and the officials chambers. The latrine block was located north of the barracks, directly at the rampart. A number of stoves and kitchens were located on the inside of the western fragment of the fortifications, separated from the barracks by the via sangularis road.

   There were bathhouses on the south side of via principalis. They were one of the first buildings built of stone and are dated to 75 AD. They were a huge complex with a length of 110 meters, including a large, open courtyard with a swimming pool and a great number of buildings in which there were baths and an exercise hall. The yard called the palaestra was used for practicing exercises and for playing games in the open air. At its northern end was a small building with an apse (nymphaeum), housing a fountain, supplying water through a lead pipe a longitudinal pool (natatio) with a length of 41 meters, running through most of the courtyard. Water dripped down the stairs from the fountain, probably flowing from the mouth of the carved dolphin. The pool, 1.2 to 1.6 meters deep, contained an impressive 365 thousand liters of water. The main bathhouse building consisted of three spacious halls: a cold bath (frigidarium), warm bath (tepidarium) and hot bath (caldarium), built of stone and topped with concrete vaults. On the north side they were adjacent to the elongated three-aisle building in the form of a basilica and a smaller heated changing room (apodyterium), added about 150 A.D. In the latter, a large apse was distinguished, probably housing a statue, while timber side lockers were placed along the side walls.

   On both sides of the bath complex, in front of the via principlais, there were already mentioned houses for the tribunes and other senior officers, while in the south-west corner of the fortress, behind the houses of the tribunes there were three granaries and a large building with a courtyard, which served as a warehouse. Excavations have revealed that it was used to store military equipment. On the eastern side of the bath complex, a hospital was most likely identified.
   West of the fort, just outside its fortifications, there was an amphitheater. It was built of earth and stone with external buttresses around the perimeter. Higher parts, benches and balustrades were probably timber. Two main entrances (portae pompae) led directly to the arena and six smaller, regularly spaced gates, intended for both viewers and performers. The amphitheater could accommodate up to 6,000 people (i.e. slightly more than the state of a full legion) who could enter it after purchasing a ticket in the form of a lead token. The main entrances in the outer parts were given stone barrel vaults, while the parts closer to the arena were uncovered. The entrances were closed with wooden doors, probably double-leaf at the main gates. Staircases led from the side entrances to the stands, with the two side entrances at the short axis of the amphitheater having two flight of stairs, flanking the rooms where gladiators had stayed before the fight. The eastern stairs were slightly wider and probably led to the main balcony, or alcove, where the most important officials sat. Throughout the entire length of the arena a channel led under it, effectively getting rid of rainwater. Originally, the surface was probably covered with gravel to prevent slipping during gladiatorial fights or animal shows. The walls around the arena were plastered and covered with red lines imitating stone ashlar.

Current state

   Until today, Caerleon has preserved many elements of the ancient Isca fort. The amphitheater survived in the best condition, even now it is use for mass outdoor events, staging and historical reconstructions. Admission to its area, with the exception of special events, is free. To the north-west of it you can see relics of legionary barracks, unveiled during archaeological research. In the town center there is the Museum of Roman Baths with foundations of buildings, mosaics and reconstruction of the pool. The museum is run by Cadw, so the opening times are exactly the same as in the nearby National Museum of the Roman Legion. There is an excellent exposition of artifacts found in the area, as well as reconstruction of the legionaries quarters. Like other national museums and galleries in Wales, access to it is free. In Caerleon, fragments of defensive walls on the south side have also been preserved.

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Knight J., Caerleon Roman Fortress, Cardiff 2003.

Website, Caerleon Town Walls.
Website, Caerleon roman fort.