Iserninus

Saint Iserninus (Isernius, in Orthodoxy Iserninus of Aghade), bishop of Kilcullen, was an Irish missionary and bishop of the fifth century, who died about 456. His commemoration is on 6 December, according to one source.

He is thought to have been a Briton or an Irishman by birth and to have preached in Ireland. His name is linked with Saints Patrick and Auxilius in the work of preaching in the south of the island. More recent research links him sometimes not with Patrick but with Palladius. The historian Charles Thomas says that current opinion perhaps inclines to link Secundinus, Auxilius and Iserninus rather with Palladius than with Patrick.

According to tradition, he preached in the lands of the Uí Cheinnselaig, in Leinster. His original name was Fith, and he may have been ordained deacon at Auxerre, together with Patrick and Auxilius. The Annals of Ulster mention him as a bishop and show that he began his mission in the year 439. According to Patrick F. Moran, Saint Patrick entrusted to Auxilius and Iserninus the valley of the river Liffey.

According to a tradition at Aghade, in County Carlow, Iserninus founded a church there and was buried there. He is also called the founder of the church at Old Kilcullen, where he was reputedly made bishop by Saint Patrick, perhaps together with Saint Mactail. Kilcullen began as a monastic settlement, in the period around 448. The choice of the place was perhaps connected with the nearby Dun Ailinne, a ceremonial site related to the kings of Leinster.