The castle of Morlais was erected by Gilbert de Clare around 1288 on the northernmost boundary of his Glamorgan lordship, to extend the influence of the de Clare family on the territory of his neighbor, Humphrey de Bohun, Earl of Hereford. The name of the castle originated from a nearby river, which in the Celtic language meant mavr (great) and glais (stream). Construction of Morlais immediately led to tension with Humphrey de Bohun. The dispute ended in 1291 with a skirmish, known as the Battle of Maes Vaynor. After this event, king Edward I intervened to solve this local, but potentially destabilizing conflict. Both Gilbert and Humphrey were fined and spent a short time in the Tower of London prison. Gilbert was punished with a larger fine of 10,000 marks due to the construction of the Morlais castle. The king’s intervention stopped works on the castle and it is uncertain whether it were ever resumed. Certainly, however, the stronghold remained in use, because it was captured by the Welsh during the revolt of Madog ap Llywelyn in 1294. After the suppression of the rebellion, the castle returned to the hands of the family de Clare, but the death of Gilbert de Clare in 1295 caused the abandonment of Morlais and falling it into ruin.
The castle occupied the top of a limestone hill, overlooking the Taf Fechan River. This place was a defensive hillfort in the Iron Age, and earlier earth fortifications were strengthened and incorporated into the new castle, giving it a unique configuration. Fortifications were in the shape of a pentagon, which was separated from the north by an internal wall to separate the upper castle (inner ward). It had a triangular arrangement with sides about 45 meters long and was dominated by a large round tower on the north side. Its diameter was 17 meters. The south side of the upper castle was guarded by a horseshoe tower, placed in the middle of the inner curtain of the wall. A four-sided building was placed between them.
Quite unusually, the lower castle (outer ward) also had a large cylindrical tower, probably in the keep type, on the south-eastern side. It had an ogival entry portal and a vaulted ground floor supported by a single, massive pillar. In addition to it, the lower castle was reinforced by five consecutive cylindrical towers, one of which was extended far ahead of the defensive walls southward, in order to flank the gateway. At the ward of the lower castle, by the inner faces of the defensive walls, there were erected an utility buildings, and perhaps a building of a great hall. Especially the over 20-meter long building with thick walls on the eastern side stood out. In the middle of the ward there was a large rainwater tank. From the north, south and east sides, the castle was surrounded by a wide, dry moat (ditch), carved into the rock.
The castle has not survived to modern times. Its layout is best seen from aerial view, only the remains of a dry moat, a water reservoir at the outer ward and small fragments of walls are visible on the ground. The most interesting element is the surviving chamber of a cylindrical keep with a preserved central pillar, vaults and an ogival entrance portal. Entrance to the castle area is free.
Kenyon J., The medieval castles of Wales, Cardiff 2010.
Website castlesfortsbattles.co.uk, Morlais castle.