But its most usual Welsh name is _Caer Cybi_, (Fort of Cybi,) so called from St. Cybi. History records the following account of this singular and extraordinary personage.—Holyhead was the residence of a British Saint, named Corincus, or Cybi, son of Solomon, Duke of Cornwall; who, it is said, about the middle of the fourth century, after having lived a very religious life for 20 years, went over to France, to Hilary, Bishop of Poictiers; and finding favour with the Bishop, was ordained by him, and officiated as his assistant until the Bishop’s death. He then returned to his native place; but on account of tribulation in the country, and some painful occurrences in the circumstances of his family, he left home again, and arrived at St. David’s, and ultimately crossed over to Ireland; and after residing there four years, returned and settled in Holyhead. A Prince in Anglesey, out of compassion to him, in consequence of his low pecuniary circumstances, gave him a castle, which was in the neighbourhood. Cybi founded a small monastery within the castle walls, and the establishment was called Côr Cybi, in allusion to the monastery, or Caer Cybi, in reference to the castle walls. Mr. Pennant presumes that the name of the town has originated from the castle walls, the remains of which are still to be seen. Mr. Morris says, that Caer Cybi, lived at the time of the dissolution of the Roman Empire in Britain, and was contemporary, and on great friendship with Seiriol, an eminent Saint, of Priestholme, or Ynys Seiriol, (Seiriol’s Island,) near Beaumaris. St. Cybi, observes Tanner, flourished about A.D. 380, and founded a small monastery in Holyhead. In the beginning of the 15th century, the Irish fleet invaded Anglesey; and after committing some depredations, returned to Ireland, taking with them the shrine of St. Cybi, which trophy they deposited among the relics in Christ’s church. Whether this town took its name from the Irish, who very early resided here,—or from its number of chapels,—or from the interment of the pious,—or from the legend of St. Bride,—or from the Saint who dwelt within its ancient fort,—is surely now of very little consequence. About A.D. 389, the Irish, under the command of Serigi, (the Rover,) landed in Anglesey; and having defeated the natives, took possession of the Island. On this invasion, _Caswallon-Llaw-Hir_, (or the longhanded) Prince of Wales, came to the relief of Mona; and having routed the enemy, pursued them to Holyhead, where their fleet lay; here they fought a second battle, in which Caswallon slew Serigi, the Irish commander, with his own hand. It is said that in this action the tribe of Caswallon put the fetters of their horses upon their own legs, by two and two, to shew their determination was, Their country, parents, children, save, Or fill one great and glorious grave!