KILBEGGAN was founded in 1150 and colonized with monks from Mellifont. It is thought that the founder was a member of the MacCoghlan family, the chief family in the district. The site had previously been occupied by an early Irish monastery, founded by St. Beccan in the fifth or sixth century. The Latin name of the abbey follows a straightforward religious formula, Benedicto Dei, 'the blessing of God'. O’Catharnaigh, the great priest of Clonmacnois, died at the abbey in 1196 and Melaghlin MacCoghlan, prince of Devlin, died in pilgrimage to the abbey in 1213. In 1217, the abbey was involved in the ‘riot of Jerpoint’ and the abbot was duly punished for his involvement. Following the ‘conspiracy of Mellifont’ (1216-1228) the Irish Cistercian houses were reorganized and Kilbeggan was made subject to Buildwas. Hugh O’Malone, bishop of Clonmacnois, was buried in the abbey in 1236.

U1157.4 The successor of Patrick (namely, the archbishop of Ireland) consecrated the church of the Monks [of Mellifont, near Drogheda, in presence of the clergy of Ireland, that is, of the Legate and of Ua Osein and of Grenne and of the other bishops and in presence of many of the laity, around Ua Lachlainn, that is, around the king of Ireland and Donnchadh Ua Cerbaill and Tigernan Ua Ruairc. Moreover, Muircertach Ua Lochlainn gave eight score cows and three score ounces of gold to the Lord and to the clergy. He gave also a townland at Drochait-atha to the clergy, namely, Finnabhair-na-ningen. And three score ounces of gold [were given] by Ua Cerbaill and three score ounces more by the daughter of Ua Mael-Sechlainn, [namely] by the wife of Tigernan Ua Ruairc.

MELLIFONT, a parish, partly in the barony of UPPER SLANE, county of MEATH, and partly in that of FERRARD, county of LOUTH, and province of LEINSTER, 4 miles (N.) from Drogheda, near the road to Ardee, by way of Collon; containing, with the parish of Tullyallen. This place derived its chief celebrity from the foundation of a monastery in 1142, by Donough McCorvoill or Carrol, Prince of Uriel, for Cistercian monks sent over by St. Bernard from his abbey of Clairvaux, and of which Christian O'Conarchy, the first abbot, was, in 1150, consecrated Bishop of Lismore.

RUINS OF MELLIFONT ABBEY, CO. LOUTH. -These highly interesting ruins lie in the midst of a beautiful lowland vale, rather that deep valley - a feature of scenery peculiar to the more fertile portions of Ireland. Mellifont is not a Gaelic name, and bears a Latin stamp upon it. The abbey was founded and endowed by O'Carrell, Prince of Oriel, in 1142, and was the first establishment of the Cistercian Order of monks in Ireland. ABBEYDORNEY, also known as Odorney or Kyrie Eleison, was founded in 1154 with monks from Monasteranenagh. Christian O’Conarchy, the first abbot of Mellifont Abbey, retired to the abbey in later life, where he died and was buried in 1186. In 1227 the abbot of Abbeydorney was deposed for his involvement in the ‘conspiracy of Mellifont’ (1216-28).

In 1157 a great synod, at which the Archbishop of Armagh, then apostolic legate, and many princes and bishops were present, was held here for the consecration of the church, on which occasion, among numerous munificent benefactors, Devorghal, wife of Tiernan O'Rourk, Prince of Breffny, who afterwards died here in seclusion, presented 60 oz. of gold, a chalice of the same metal for the high altar, and furniture for nine other altars in the church. The ample endowments of the abbey were confirmed by charter of Hen. II., and by King John, who augmented its possessions; and in 1347 and 1349, Edw. III. greatly extended its possessions and privileges; he granted to the abbot the power of life and death within his territories, and the liberty of acquiring a burgage holding in the town of Drogheda, for the residence of the abbots during the sittings of parliament and other great councils.

In 1450 and again after 1460, the abbot of Abbeydorney complained to the pope about unjust subjugation and unlawful payments enforced by James de Geraldinis, Earl of Desmond, and others. In 1453 the abbot was accused of misrule by a monk of Monasteranenagh. Following the Dissolution, Edmund, lord Kerry, was granted Abbeydorney, and other monasteries, and was created Baron of Odorney and Viscount of Kilmaule. However, the changes imposed by the Dissolution had little immediate impact on Abbeydorney. Although the monastic land became secularised, the monks themselves were not dispersed. In fact the abbot of Abbeydorney remained active for forty years after the initial closures took place and was stopped only in 1577 when he was shot at Lixnaw Castle. The site of the monastery is now used as a graveyard. For centuries it has been customary for local families to bury their dead within the confines of a medieval abbey or friary: Abbeydorney is a notorious example. The remains of the old cloister garth are weighted down with relatively modern tombs and monuments. The chief remnant of the monastery is the abbey church with a projecting western tower, all of which dates from the fifteenth century.

In 1471 and 1472, parliament disannulled the grants, rent-charges, annuities, leases and alienations made by the late Abbot John. In 1540, Richard Conter, the last abbot, resigned the monastery into the King's hands and received a pension of £40 per ann. for life. After the dissolution, the monastery and its revenues, at that time valued at £315. 19s., were, on account of the difficulty of defending these possessions against the incursions of the native Irish, granted to Sir Gerald Moore, who converted the abbey into a baronial residence and place of defence.

At the time of Dissolution the annual income of KILBEGGAN abbey was valued at £13, making it one of the poorest Cistercian abbeys in Ireland. The abbey was dissolved in 1539 and the property was later granted to the Lambert family. In the eighteenth century, the ruins were replaced by a Protestant church. Today there are no visible remains of the abbey and the site is now occupied by the ruins of the Protestant church.

Although it was originally a vast structure, or combination of structures, time, war and vandalism have reduced the ruins to their present scanty proportions. Apart from its interests, as a relic of Ireland's epoch of scholastic and ecclesiastical glory, Mellifont is famous as the place in which Dearvorgil, the faithless wife of O'Ruarc, whose fall from grace with McMurrough led to the Anglo Norman invasion, died in 1193. Mellifont was witnessed, on March 30, 1603, the saddest day that ever dawned on Ireland, the surrender of Hugh Ó Neill, the victor of the Yellow Ford and Drumfluich, to Lord Deputy Mountjoy, after a bloody struggle of eight long years, in which the great Earl of Tyrone, as the English called Ó Neill, won imperishable renown.

Though situated so near the border of the English pale, the place maintained itself in security against all the attacks of the Irish, till, in the war of 1641, it was besieged by a strong body of the insurgents, when the garrison, consisting only of 15 horse and 22 foot, made a vigorous defence, in which they killed 120 of the enemy, and on their ammunition being exhausted, forced their way through the besiegers and retreated to Drogheda in safety, with the exception of 11 men who were intercepted and put to the sword. The castle was plundered by the insurgents, who, taking advantage of the absence of Lord Moore with his troop of 66 horsemen for the protection of Drogheda, desolated the place and put the servants to death. Mellifont continued for some time after to be the chief residence of the Moore family, till the Earl of Drogheda removed to Monastereven, now Moore abbey, in the county of Kildare, since which time this once magnificent pile of building has become a heap of ruins.

The parish is situated in a beautiful small valley intersected by the Mattock rivulet, which flows into the river Boyne.

In the Roman Catholic divisions it is also part of the union or district of Tullyallen.

The ruins of the ancient abbey, for which this parish is chiefly celebrated, consist principally of the lofty gateway leading into the area of the abbey grounds, and a massive square tower carried up on one side to a considerable height, and forming a strong protection against the frequent assaults to which the place was exposed; it is connected with the rock by a wall, affording entrance only through a low circular archway. Within the area are the elegant remains of St. Bernard's chapel, the splendid doorway of which, a highly enriched and deeply receding pointed arch in the most elaborate style of Norman embellishment, has been removed.

The interior of the chapel is plainly groined with arches springing from columns on the side walls with ornamented capitals, and lighted with an east window of two lights, enriched with delicate tracery, and with three windows of similar design on each side. The baptistry, an octagonal building of great beauty, has only four of the walls remaining, each resting on an arch of graceful form and richly moulded; the roof is wanting but within are the corbels on the walls from which the arches sprung for its support; above the roof of this building was a reservoir of water, from which every part of the monastery was supplied. There are also the foundations of a spacious quadrangular building, probably the cloisters; and near the summit of the hill is a large cemetery, with some remains of a church, apparently of a much later date; there are numerous fragments of richly sculptured pillars scattered over the site, and though these very interesting ruins afford but an imperfect idea of the original grandeur of this celebrated monastery, they present in their details many of the richest specimens of architectural embellishment to be found in any part of the country.