Catholic Encyclopedia (1913)/Diocese of Ardagh
Ardagh, an Irish diocese in the ecclesiastical province of Armagh, takes its name from a town in the parish and barony of same name in county Longford, province of Leinster. Here, according to Colgan, St. Patrick baptized Maine, Lord of South Teffia, in Longford, built a church in a place called Ardachadh, which to this day is a see, and consecrated Mel, the son of his sister Darerca, the bishop leaving with him Melchu (Mel's brother) as co-bishop. Archbishop Healy accepts this statement, though Lanigan and O'Hanlon reject the co-episcopate of the brothers. The church of Ardagh was founded in 454 and is justly held to have been one of the most ancient in Ireland. St. Mel, or Moel, was not only the bishop of this church, but also abbot of the adjoining monastery, and is yet patron of the diocese. Outside the town are the ruins of a small primitive church the remains of which are of cyclopean character. The see originally comprised the country of the Eastern Conmaice. It consisted of the territory of the O'Ferals and the O'Quinns in the county Longford, called Annally, and the territory of Muintir Eolais, i.e. of MacRannal (O'Reynolds) in Leitrim. From the death of St. Mel to the coming of the English under Henry II (1169) the extant records of episcopal succession (for which see Gams, Series episcoporum Ratisbon, 1873-1876) are uncertain, meagre, and broken. St. Erard, who ruled over this diocese in 754, having journeyed to Rome with some companions, died at Ratisbon, of which see he is said to have been bishop. In the fourteenth and fifteenth centuries several members of the O'Feral clan occupied the chair of St. Mel. The Diocese of Clonmacnoise was united to that of Ardagh in 1729, during the episcopate of Bishop Flynn, and so continues. The modern Diocese of Ardagh includes nearly all of Longford, the greater part of Leitrim, and portions of King's County, Westmeath, Roscommon, and Sligo. There is a cathedral chapter of Ardagh and Clonmacnoise, and there are forty-one parishes in the united dioceses. The seat of the bishop is at Longford, where a fine cathedral and a diocesan seminary have been erected.