We are thus introduced to an entirely new group of castles, Rhuddlan being the only one which we have heard of before. But it is highly probable that most of these castles were originally raised by the earls of Chester or Shrewsbury, and were in Henry's hands by escheat.
*BASINGWERK.--The _werk_ referred to in this name has probably nothing to do with the castle, but refers to Wat's Dyke, which reaches the Dee at this point. The abbey at this place was founded by an earl of Chester,[869] which makes it probable that the castle also was originally his work, especially as Wendover says that Henry _rebuilt_ it. There is no trace of a castle near the abbey,[870] but less than a mile off, near Holywell Church, there is a headland called Bryn y Castell, with a small mound at the farther end, which has far more claim to be the site of Basingwerk Castle, especially as it is mentioned in John's reign (when it was retaken from the Welsh) as the castle of Haliwell.[871]
OVERTON, in East Denbigh, on the middle course of the Dee. In custody of Roger de Powys for the king in 1159-1160. As Leland speaks of the ditches and hill of the castle, it was probably a motte-castle of the usual type. "One parte of the ditches and Hille of the castel yet remaynith; the residew is in the botom of Dee."[872] It is probably all there now, as not a vestige can be traced. [B. T. S.]
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.