O'Heyne tells us, "This convent was built for the Dominicans in 1400, by O'Ferrall, a very illustrious, ancient, and, for those times, powerful dynast of Annaly". Harris, in his edition of _Sir James Ware's Antiquities_, distinctly names Cornelius O'Ferrall, the Dominican Bishop of Ardagh, as the founder. De Burgo, in his _Hibernia Dominicana_, from which most of our information is taken, shows that in the year 1400, in which the Convent of Saint Brigid was founded, Adam Lyons, a Dominican Friar, succeeded Gilbert MacBrady in the See of Ardagh; that Adam Lyons died in 1416, and was succeeded by Cornelius O'Ferrall, who was consecrated in February, 1418, when the Convent of Saint Brigid had been built and inhabited nearly eighteen years. Hence, it is very clear, that if Cornelius O'Ferrall was the founder, it must have been before his consecration as bishop, and very probably before his admission to Religion as a Dominican. It is not improbable that, like others of his name, he was dynast of Annaly before he assumed the mitre of Ardagh, and that having in his boyhood been a pupil of the Dominicans, as we learn from the Bull of his consecration, he had founded this convent for them long before he thought of joining the order himself. Cornelius O'Ferrall died, "celebrated for his liberality to the poor", as Ware tells us, for which he was popularly known by the name "_Eleemosynarius_", or the "_Almsgiver_", and he was buried in the Abbey of Saint Brigid in 1424. The family of the O'Ferralls made repeated and ample grants to the convent, and, after the example of Bishop Cornelius, made the abbey their family burial place. The church attached to the convent stood on the site now occupied by the Protestant parochial church of Longford, on the north side of the river Camlin. From it a raised causeway or road led through the meadows by the river side, to the coenobium, or convent proper, which stood on the opposite, or south side of the river, about a quarter of a mile distant. This church was destroyed by fire, and the convent reduced to ruins in 1428. The extent and character of this first convent may be gathered from O'Heyne, who says, it was a most extensive and magnificent structure, as shown by the magnitude of the ruins still remaining in his day (1750). The importance and influence which, in a very few years, the abbey had been able to attain, may be inferred from the fact, that Bulls were issued by several popes, granting indulgences to the faithful who would contribute to its restoration.