Tomen Y Mur Roman Fort

Flavian Auxiliary Fort (AD 69–96) and Industry

The Roman Fort at Tomen-y-Mur was first recorded as Roman by the antiquary Robert Vaughan around 1630, the first plan was published by Pennant in 1781 and the first excavations were conducted in 1850 and 1868. This fort stands on a small prominence on the eastern side of Ffestiniog Vale about half way down the slopes of Myndd Maentwrog overlooking the Llyn Trawsfynydd from the north-east. A small stream passes just outside the south-eastern defences and feeds into the lake next to the site of the nuclear power station. The site is nowadays dominated by a Norman motte, and it is possible that the fort’s defences acted as this Medieval castle’s outer enclosure or bailey.

Dating evidence suggests that the fort was built by governor Agricola c. A.D. 78.  This was during the period that Julius Frontinus was governor of Britain, between AD74 and AD78, when the system of forts linked by roads was first established in NW Wales. The earlier fort had earth and timber defences consisting of two banks topped by a timber palisade. The early fort forms a rectangle some 158m by 110m internally, with its long axis sloping downhill from NW to SE.  Between the banks there were initially two ditches, but these were later replaced by a single ditch. Gateways are recorded in the middle of the south-east defences and in the south-west defences off-set to the east by a ratio of about 3:2, which is the typical Roman military tertiata pattern; the fort therefore faced east-south-east.

The second phase fort, probably constructed in about AD120 when Hadrian was emperor, had an internal area of 122m by 110m and was defended by a stone wall, as well as the existing earth banks and ditches. On three sides the wall stood on top of the earlier inner bank, but on the NW a new ditch was dug and bank created.  It was finally abandoned c.140 and never re-occupied. The latest piece of Samian recorded at the site was of “Potter X-6”, who produced wares c. A.D. 125-150; two pieces of decorated ware were dated c.100-120.

Many features have been observed from the air. A cross-ditch at the north-west end of the fort reduced the occupation area by about one-fifth. An annexe measuring about 175 by 150 feet (c.53 x 46 m) and enclosing an additional ½-acre (c.0.24 ha), was attached to the northern end of the north-western defences. The outline of a stone-built principia measuring about 80 x 85 feet (c.24 x 26 m) and facing south-east in the centre of the fort, was observed from the air as parch-marks in the dry Summer of 1976; other internal features were also observed at the same time.

Tomen y Mur is the Welsh name for the site which means “mound of the wall”; as it is an allusion to Norman Motte that stands within the remains of the Roman embankments, hence cannot be earlier than the 11th century. As no written references about the site have survived, the fort’s Roman name is unknown.

There is an Tomen Y Mur Arena or Amphitheatre to the north east of the fort, and the remains of Practice Camps to the north west. A Roman Bath house and mansio are to its south east.

Inscribed Stones from Tomen-y-Mur?

Six stones in the structure of Harlech Castle bearing inscriptions in Latin, which reputedly originated from the Tomen-y-Mur fort. All are recorded below:

RIB 419 - Inscription

… propraetorian [legate ..

[...]BỊ[...]
[...] PRO[...]

No commentary.


RIB 423 - Centurial stone of Julius Perpetuus

The century of Julius Perpetuus (built) 21 feet.

𐆛 IVL
PERPETVI
P XXI

No commentary. Addenda from RIB+add. (1995): This building-stone, part of a group of eight (RIB 420-427) which range in thickness D from 0.24 to 0.41 m, almost certainly belongs to the stone defences of the reduced fort: Stephens, AC 137 (1988), 104.


RIB 424 - Centurial stone of Julius Perpetuus

The century of Julius Perpetuus (built) 39 feet.

𐆛 IVLI
PERPETVI
P XXXIX

No commentary. Addenda from RIB+add. (1995): This building-stone, part of a group of eight (RIB 420-427) which range in thickness D from 0.24 to 0.41 m, almost certainly belongs to the stone defences of the reduced fort: Stephens, AC 137 (1988), 104.


RIB 425 - Centurial stone of Perpetuus

The century of Perpetuus (built) 20 feet.

𐆛 PERPE
TVI
P XX

No commentary. Addenda from RIB+add. (1995): This building-stone, part of a group of eight (RIB 420-427) which range in thickness D from 0.24 to 0.41 m, almost certainly belongs to the stone defences of the reduced fort: Stephens, AC 137 (1988), 104.


RIB 426 - Centurial stone of Perpetuus

The century of Perpetuus (built) 21 feet.

𐆛 PERPE
P XXI

Although this stone does not seem to have been read fully until 1908 (by F.H.), it was probably found at about the same time as the other inscriptions of Perpetuus (RIB 423, 424, 427) and ought to be the second example read as pxx in 1868 and the fifth stone ‘from the same locality but not very legible’, as recorded in 1871. Addenda from RIB+add. (1995): This building-stone, part of a group of eight (RIB 420-427) which range in thickness D from 0.24 to 0.41 m, almost certainly belongs to the stone defences of the reduced fort: Stephens, AC 137 (1988), 104.


RIB 427 - Centurial stone of Perpetuus

The century of Perpetuus (built) 22 feet.

𐆛 PERPETVI
P XXII

No commentary. Addenda from RIB+add. (1995): This building-stone, part of a group of eight (RIB 420-427) which range in thickness D from 0.24 to 0.41 m, almost certainly belongs to the stone defences of the reduced fort: Stephens, AC 137 (1988), 104.

References for Tomen Y Mur

  • Military Aspects of Roman Wales by Professor F. Haverfield (London 1910), pp.43-46;
  • Air Reconnaissance of Southern Britain by J.K. St. Joseph in J.R.S. xliii (1953) p.87;
  • Air Reconnaissance in Britain, 1958-1960 by J.K. St. Joseph in J.R.S. li (1961) pp.130/31;
  • Britons and the Roman Army by Dr. Grace Simpson (London 1964);
  • Air Reconnaissance in Britain, 1961-1964 by J.K. St. Joseph in J.R.S. lv (1965) p.86;
  • The Roman Inscriptions of Britain by R.G. Collingwood and R.P. Wright (Oxford 1965);
  • Air Reconnaissance in Britain, 1973-76 by J.K. St. Joseph in J.R.S. lxvii (1977) p.151;

Map References for Tomen Y Mur

OS National Grid Reference: SH705387
Dimensions: c.510 x 390 ft (c.155 x 120 m)
Area: c.4½ acres (c.1.7 ha)

Roman Roads near Tomen Y Mur

SSE (14) to Brithdir (Gwynedd) N (12) to Brynygefeiliav (Gwynedd) Possible road: WNW (14) to Penllystyn (Gwynedd)

Sites near Tomen Y Mur Roman Fort