NGRef: ST1397
OSMap: LR171
Type: Fort, Camp, Practice Work, Industry

The second century fort at Gelly Gaer
S (6) to Caerphilly (Mid Glamorgan)
NW (8) to Penydarren (Mid Glamorgan)

gelligaer - "The Fort of the Grove"

ST134970 c.404 x 385 ft
(c.123 x 117.3 m)
c.3½ acres
(c.1.44 ha)

Flavian pottery suggests an early construction date for the original timber fort, which was replaced in stone around the turn of the second century, at the same time a bath-house was built within an annexe attached to the fort's south-eastern defences. Antonine pottery dated c.170AD confirms a continuation of occupancy into these times. The well of the principia (regimental H.Q. building) in the centre of the fort was filled with debris around the period 196/7AD, which may indicate either demolition of the interior buildings by the Romans themselves as part of a planned withdrawal, or destruction of the fort by an enemy force. This was a particularly unsettled period of Romano-British history, and both of these scenario's are possible. Either way, the fort was soon reoccupied, as the granaries were rebuilt sometime during the Severan period (c.197-211AD), and continued occupation at the fort is attested by the presence of third and fourth-century pottery found within the defences.

gelligaer Fort, Annexe and Marching Camp
The second century fort and annexe, with nearby temporary camp, at Gelly Gaer in Glamorgan
Adapted from Collingwood The Archaeology of Roman Britain (fig.6).

"gelligaer (Glamorganshire; Fig. 6) is 404 by 385 feet externally, with a 20-foot composite rampart composed of a 4-foot revetment, 13 feet of clay, and a 3-foot inner revetment - the last an unusual detail. Its internal area is rather over 21 acres. It has four double gates, with guard-rooms, centrally placed in the sides; each passage-way is 11 feet wide. There is a single 20-foot ditch with a 5-foot berm. Inside, the buildings are all of stone. They include (beside the usual headquarters, commandant's house. and granaries) six L-shaped barrack-blocks for the six centuries of a cohors quingenaria, and five other buildings for various other purposes. It was built between A.D. 103 and 112 and not occupied later than Hadrian's reign. Outside the fort are a temporary camp, a gravelled parade ground, and an entrenched annexe containing a bath-house (Ward, The Roman Fort of gelligaer, 1903 : Haverfield, Military Aspects of Roman Wales, § xix)." (Collingwood, p.40)

The Supposed Temporary Marching Camp

ST133972 c.570 x 420 ft
(c.174 x 128 m)
c.5½ acres
(c.2.22 ha)

This camp lies only about 165 feet (c.50 m) outside the north-west defences of the fort and was seemingly aligned with them. The enclosure measures about 570 feet from north-east to south-west by about 420 feet transversely (c.174 x 128 m), an area of around 5½ acres (c.2.22 ha). The entire perimeter of the camp is known but only two gateways are recorded, one placed centrally in the north-east side, the other in the north-west side about one-third of the way in from the western corner-angle; the camp therefore faced towards the south-west and the Silures.

When excavated by Ward in 1960 the defences were found to consist of an earthen bank in access of 20 feet (c.6.1 m) wide at its base, fronted by two ditches, each about 11¼ feet wide (c.3.4 m) separated by a berm of around 7½ feet (c.2.3 m). Further investigations by Jarrett in 1963 in the southern angle revealed the post-holes of timber buildings with at least two construction phases, the final phase showing signs of destruction by fire. In light of these findings it is assumed that this camp represents the remains of a Flavian or Trajanic turf and timber fort, the precursor of the later stone-built fort.

Although best observed from the air, the defences of this encampment may still be traced in the fields on the opposite side of the access road from the Rectory as a slight bank only 1 foot high and almost 40 feet wide (c.0.3 x 12 m).

The Military Practice Works on gelligaer Common

There are at least another five small camps nearby; four on gelligaer Common about 1¼ miles to the north of the fort and another along the old road, the 'Heol Adam', about 1½ miles to the north-west. All of these fortifications are much too small and are situated too close together to have served any tactical military purpose and have been categorised as 'military practice works', earthworks constructed by Roman troops on exercise. All of these 'practice works' are shown on the Ordnance Survey Explorer® map of the area.

ST138992(e) 100 x 100 ft
(c.30 x 30 m)
c.¼ acre
(c.0.09 ha)
ST138992(w) 98 x 84 ft
(c.30 x 25 m)
c.0.19 acre
(c.0.07 ha)
ST131991 80½ x 68 ft
(c.24 x 20 m)
c.0.12 acre
(c.0.05 ha)
ST116986 78 x 75 ft
(c.23 x 22 m)
c.0.13 acre
(c.0.05 ha)
ST129994 82 x 75 ft
(c.24 x 22 m)
c.0.14 acre
(c.0.06 ha)

Epigraphic Evidence from gelligaer

Centurial Stone from gelligaer


"The century of Demius [made this]."

(RIB 400; centurial stone)

There are five inscriptions on stone recorded in the R.I.B. for gelligaer, three of which mention the emperor Trajan (vide infra) and another which reads ...GERM ... ... TRIB P P ...PM I (RIB 398), may also be attributed to him. The only other inscription is a 'centurial stone' recording the work done by a particular century of men which, unfortunately, does not name their unit (vide supra). The garrison unit of the fort is not known.

Dedicatory Inscriptions of the Emperor Trajan


"Imperator Caesar Nerva Trajanus Augustus Germanicus Dacicus,¹ son of the divine Nerva, hight priest, holder of tribunician power, father of his country, consul five times, hailed Imperator in the field four times."

(RIB 397; dated: 103-112AD)


"For Imperator Caesar Nerva Trajanus, son of the divine Nerva."

(RIB 400a; JRS xlviii (1958), p.151, no.6; dated: 101-117AD?)

... TRAIANO ... PONT ... COS V

"[...] Trajanus [...] pontifex [...] consul five times."

(RIB 399; dated: 103-112AD)

Other Nearby Roman Sites

There are several practice works in the immediate area of the gelligaer fort. There is also a large temporary marching camp some 9½ miles to the west at Twyn-y-Briddallt (ST0098).

See: Caer Rufeinig Gelliger Roman Fort By Richard J Brewer, Amgueddfa Cymru – National Museum Wales 2011
An Inventory of the Ancient Monuments in Glamorgan by the RCAHMW (HMSO, Cardiff) vol.I, pt.ii, pp.95-8 & fig.53.
Air Reconnaissance in Britain, 1965-1968 by J.K. St. Joseph in J.R.S. lix (1969) p.126;
Air Reconnaissance in Britain, 1958-1960 by J.K. St. Joseph in J.R.S. li (1961) p.126;
The Roman Inscriptions of Britain by R.G. Collingwood and R.P. Wright (Oxford 1965);
The Archaeology of Roman Britain by R.G. Collingwood (Methuen, London, 1930).
All English translations, including any inherent mistakes, are my own.

Many thanks to Roger Cheesman who pointed out errors in my geography.

Page Citation: Kevan White (2018) "Roman Britain: GELLIGAER"