The few records we have concerning Caswallon-Llaw-Hir, delineate the great man and the hero. He was the eldest son of Einion Yrth, sovereign of North Wales. The Triads record him with Rhiwallon son of Urier, and Belyn, as the chiefs of the three golden-banded tribes. In consequence of the signal bravery of the people of Caswallon, in the great battle of Holyhead, their leader obtained a privilege of wearing the golden bands, which denoted that no other power had jurisdiction there except the voice of the national diet, assembled on extraordinary occasions. After this conquest, a chapel was erected, within the fortification of Holyhead, over Serigi, called _Eglwys y Bedd_, i.e., the church of the grave. This church was afterwards endowed with distinct revenues from those of the Collegiate Church, as appears by the College leases; it was called in the British manuscript, _Capel Llan y Gwyddel_, or the Chapel of the Irishman. At length it fell into ruin, and remained disused for ages; and was ultimately removed, in order to render the way to the church more commodious. In digging, the workmen found a stone coffin, or chest, under an arch in the north side of the chancel, with human bones of a prodigious size. Serigi was canonized by his countrymen, and had in this chapel a shrine, which seems to have been held in exceedingly high repute, for several very wonderful qualities and cures; but according to an old Irish chronicle, it was carried off by some Irish rovers, and deposited in the Cathedral of Christ Church, Dublin; from whence, they were removed with many others, after the reformation, to — a place not far from Dublin, where the relics that could be preserved from that universal destruction are still kept. A religious house is said to have been erected here by Prince _Maelgwyn Gwynedd_, in the latter part of the 6th century. Maelgwyn Gwynedd endowed the See of Bangor with lands and franchises; he also built or repaired Shrewsbury, and the Castle of Harlech; also the Priory of Penmon; and was the patron of Taliesin, the Post Laureate, and prince of the celebrated Bards. A castle, now in ruins, over against the town of Conway, was originally erected by him; he was contempory with Prince Arthur:— In Arthur’s days, of ancient date, When Cambria’s chiefs elected Her Maelgwyn to the regal seat, Were Harlech’s towers erected. History says he died of the yellow fever, which then desolated the country, in the church of Llanrhos, which gave rise to an adage,— The sleep of Maelgwyn in the church of Llanrhos. Holyhead being a landing place for the enemy, was often the scene of violent encounters, between the Welsh on the one side, and the Irish, Picts, Danes, and Saxons on the other. In A.D. 914, the men of Dublin destroyed Holyhead and ravaged the Isle of Anglesey. In A.D. 958, Abloic, King of Ireland, burnt Holyhead, and spoiled the country.