The castle probably existed by 1230 when Prince Morgan ap Hywel of
Caerleon (d.1248) was warned that as a baron of the earldom of
Gloucester he owed fealty and allegiance to the royal representative
who held that land during the minority of the earl. In 1231
Morgan stood to his fealty and suffered heavy damage in the ensuing
attack by Prince Llywelyn ab Iorwerth
(d.1240). In the war of 1233-34 Morgan seems to have gone over to
the side of Prince Llywelyn leading the king to state that Llywelyn had
broken the truce between them. Morgan and Llywelyn were
certainly acting together in January 1236 when a castle belonging to
Morgan had been seized. This may have been Machen which had been
taken by Earl Gilbert Marshall of Pembroke during earlier fighting.
As the castle was not mentioned again, it is to be presumed that
it did not survive these wars. It seems likely that when Earl
Gilbert Clare (d.1295) conquered the district, rather than refortifying
this Welsh hill castle, he built Caerphilly castle in the nearby valley.
The castle is now very fragmentary, but seems to have consisted of a
rectangular ward with rounded corners about 200' square. As such
it may be Roman or even a Welsh llys.
This is set against a rocky drop to the south. There are
remains of a surrounding ditch to E&W, but the north side has been
badly ploughed out. There are some traces of a curtain to
SE&SW, but centrally in the west curtain are the foundations of a
lozenge shaped tower that apparently commanded a hole in the wall gate
just north of it.
The core of the castle undoubtedly exists against the cliff face.
Here centrally are the last remnants of a rectangular tower about
45' E-W by c.30' N-S. This would put it roughly in the Criccieth class (43'x32') sized keep. Other similar keeps exist at Dolwyddelan II (44'x31') also in Gwynedd, as well as Hopton (45'x40') and the large tower keep in the bailey at Richards Castle (45'x33') in England. The keep at Adare (43'x35') in Limerick, Ireland, is also of similar size. Other smaller rectangular keeps existed in Wales and the Marches at Carndochan, Clun, Dinas Emrys, Dolwyddelan I, Moreton Corbet, Powis, Wattlesborough, White Castle and Y Bere.
The Machen rectangular keep was built upon a rocky crag and has a
surrounding ditch that also partially covers a round tower keep on its
own 'motte' in the SE corner of the enceinte. This was about 30'
in external diameter with walls about 10' thick. A list of other round tower keeps can be found in the description of Llanstephan castle and a general list of round keeps is found under Dundrum.
Paul Martin Remfry