Has been described as a Possible Uncertain

There are uncertain remains

Alternative NamesCastle of Edernion; Edeyrnion; Dernant; Dermant
Historic CountryMerioneth
Modern Authority
1974 Authority

Dernio, or Dernant. There can be no question that Dernio is Edeyrnion, the valley stretching from Bala Lake to Corwen. Domesday Book tells us that Rainald the Sheriff, a "man" of Earl Roger of Shrewsbury, held two " fines" in Wales, Chenlei and Dernio, that is, Cynllaith and Edeyrnion. (D. B., i., 255a) Towards the end of the 11th century there must have been a Norman castle at Rug in Edeyrnion, as it was to this place that the earls of Chester and Shrewsbury enticed Griffith ap Cynan, the rightful ruler of Gwynedd ; they then sent him prisoner to Chester for twelve years. (Life of Griffith) Very likely the castle of Dernio, which Henry II. was putting into a state of defence in 1159, (Pipe Roll, 1159-1160. £4, 3s. 4d. paid to Roger de Powys "ad custodiam castelli de Dernio"; "In munitione turris de Dermant &6, 4s. od." It cannot be doubted that these two names mean the same place.) was at Rug, 1.5 miles from Corwen At any rate, the castle was in Edeyrnion, and shows that Henry was holding the northern part of Merionethshire. (Armitage 1912)

Frequently taken as Rug, but there are too many castle sites in Edernion for identification to be possible. (Hogg and King, 1963)

Not scheduled

Not Listed

County Historic Environment Record
OS Map Grid Reference

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  • King, D.J.C., 1983, Castellarium Anglicanum (London: Kraus) Vol. 1 p. 278
  • Armitage, Ella, 1912, The Early Norman Castles of the British Isles (London: John Murray) p. 267-8 online copy


  • Hogg, A.H.A. and King, D.J.C., 1963, 'Early castles in Wales and the Marches: a preliminary list' Archaeologia Cambrensis Vol. 112 p. 77-124
  • Brown, R, Allen, 1959, 'A List of Castles, 1154–1216' English Historical Review Vol. 74 p. 249-280 (Reprinted in Brown, R. Allen, 1989, Castles, conquest and charters: collected papers (Woodbridge: Boydell Press) p. 90-121) view online copy (subscription required)

Primary Sources

  • 1884 The Great Roll of the Pipe for the sixth year of the reign of King Henry II, A.D. 1159-60 (Pipe Roll Society 2) p. 26 online copy