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.[873] 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.[874] Very likely the castle of Dernio, which Henry II. was putting into a state of defence in 1159,[875] was at RUG, 1-1/2 miles from Corwen, where there is still a motte in some private grounds, and there was formerly a bailey also.[876] The place was the seat of an important family in later times. At any rate, the castle was in Edeyrnion, and shows that Henry was holding the northern part of Merionethshire. HODESLEY; undoubtedly "The Rofts" near Gresford, a motte with remains of a bailey, on a headland above the river Alyn. It is in the former lordship of Hoseley.[877] WREXHAM, the Wristlesham of the _Pipe Rolls_ (Fig. 40).--Henry was paying for the custody of this castle and that of Hoseley in 1160 and 1161. Both castles are in the district of Bromfield, which was one of the early acquisitions of the earls of Chester. Mr Palmer remarks that this district was probably ceded to the princes of Powys, in return for the help which they often rendered to the English king against other Welsh princes, as it is found as part of Powys at a later period.[878] There are no remains of any castle at Wrexham itself, but about a mile off, in Erddig Park, there is a motte and bailey of considerable size (though the motte is reduced) showing that a castle of some importance once stood there. There were formerly some remains of masonry.[879] Wat's Dyke has been utilised to form one side of the bailey. It is probable that the importance of the two Bromfield castles, Wrexham and Hoseley, was lost when the princes of Powys built their castle on Dinas Bran. *RUTHIN.--This important castle, defending the upper valley of the Clwyd, was probably in existence long before Henry II. repaired it in 1160, and may perhaps be attributed to Earl Hugh of Chester. The plan shows distinctly that it was once a motte and bailey, though the castle is now transformed into a modern house.[880]