Legionary Fort

In Britain, when the first movement of conquest was over, the legions settled down into three fortresses, at York, Chester and Caerleon.

York was the successor of an earlier fortress at Lincoln, where the Ninth Legion, Legio IX Hispana, established itself about A.D. 60 and remained until A.D. 71, when for a few years its place was taken by Legio II Adiutrix. The fortress occupied the site later given to the Roman town, and its ramparts lie below the town defences. The first rampart, an earthwork with vertical timber front and back, resting upon a timber corduroy 11 feet wide, was soon enlarged by adding a sloping front and massive timber towers. The works enclose an area of 41.5 acres (1,290 X 1,470 feet). This is on the small side for a legionary fortress, normally some 50 acres in size, but the reason for the restricted area remains unknown.

Caerleon had a predecessor at Gloucester. The site of the fortress is known to be that of the town, though evidence for early occupation also comes from north of it at Kingsholm, for which Ermine Street originally aimed. A tombstone of a soldier of the Twentieth Legion is known, and also a fine auxiliary tombstone of a Thracian trooper.

Chester was preceded by Wroxeter, which has yielded tombstones of the Fourteenth Legion (Izglo XIV Gemina Martia Victrix). This unit, however, left Britain in A.D. 66, returning for a brief sojourn in 69, and it is not certain whether its place was taken at Wroxeter by another. The fortress at Chester was not founded for some ten years, about A.D. 78, and was then occupied by Legio Il Adiutrir from Lincoln. There are, however, reasons for thinking that the site of Chester had already been occupied by an auxiliary fort.

The legionary fortress at Chester is one of the largest in the Roman Empire, and contains several unique building types. First among these is the so-called ‘elliptical building’, which has been interpreted as a major religious structure. Buildings such as this confirm that, though Roman fortresses are well understood and conform to an approximate template, the order in which buildings were laid out can and does vary, and novel buildings still await discovery.

Much the most remarkable of the earlier legionary fortresses in Britain is Inchtuthil, at the Highland gate of the Tay, which was founded by Agricola soon after A.D. 83 and systematically demolished soon after A.D. 56. The defences comprise a single ditch 20 feet wide and 6 feet deep, and a turf rampart, now 13 feet wide, but cut back to receive a stone wall 5 feet thick. The wall encloses an area of 1,620 by 1,565 feet, or 53 acres. The gateways were of timber, with twin portals recessed between two towers 20 feet square. Internal buildings comprise the headquarters (principia), officer's houses, sixty four barracks, six granaries, stores-sheds, military hospital (valetudin drill hall (basilica exercitatoria) and construction shop fabrica). Not all the buildings, however, had been constructed before the fortress was deliberately dismantled, following the transfer of Legio II Adiutrir to the Danube frontier. Inchtuthil constitutes the only example of a legionary fortress in Britain which is available for full examination. In this respect it is perhaps even more valuable than the continental stone fortresses, at Novaesium and elsewhere, which were much reconstructed. And its date, of about A.D. 83-7, places it at the moment when the Roman Army was at the height of its disciplined organisation.

What does a Fortress Look like?

The internal area of the fortress was divided into three ranges by two transverse roads. The front and rear thirds were further divided into two by longitudinal streets. Beyond this shared pattern of subdivision the buildings within fortresses, though the same in character, tended to be differently arranged according to local requirements.

The administrative centre of the legion (principia) lay in the centre of the fortress at the junction of the principal transverse street (via principalis) and one of the longitudinal streets (via praetoria). This building had an open court at the front, behind which was a cross-hall, behind which again were offices, flanking the chapel of the standards (aedes) in the centre. The building sometimes contained a sunken strong-room. The fortress is deemed to ‘face’ in the direction faced by the entrance to the principia. The commander’s residence (praetorium), which was usually a courtyard building, sometimes with a hypocaust and usually with its own integral bath-house, lay either to the rear of the principia or to one side of it.

Also within this central range were the hospital (valetudinarium), workshops (fabricae) and equipment store. The barracks of the first cohort
were located on the right-hand side of the principia, ranged parallel to the side wall, with the houses of the senior centurion on the via principalis street frontage. The accommodation for a further cohort lay on the other side. In the front third of the fortress, the praetentura, the houses of the six military tribunes, occupied the street frontage, while the barracks of the remaining cohort occupied the rest of the praetentura and the whole of the rear portion, the retentura.

Granaries (horrea), comprising long narrow buildings with flanking buttresses, with raised floors supported on posts, pilae or dwarf walls,
and also store buildings, usually occupied the areas closest to the gates. Often (as at Inchtuthil), the main streets were lined with small square
rooms, open to the street, that may have been storage or workshop premises. Often, as at Chester and Exeter, large and elaborate bath
houses were situated within the fort defences.

Locations of Legionary Forts in Roman Britain

Different Types of Legionary Fort