From History of the Irish Hierarchy by Rev. Thomas Walsh (1864):
‘Athassel, in the Barony of Clanwilliam, and on the west side of the river Suir. William Fitz Adelm de Burgo founded this abbey under the evocation of St. Edmund, king and confessor, for canons regular of St. Augustine.
A.D. 1204, the founder was interred here.
A.D. 1309, the prior was sued by Leopold de Mareys and Company, merchants of Lucca, for the sum of five hundred marcs, £2,500 sterling.
A.D. 1319, the town of Athassel was maliciously burned by the Lord John Fitz Thomas.
A.D. 1326, Richard, the Red Earl of Ulster, was interred here.
A.D. 1326, Bryan O’Brien burned Athassel to the ground.
A.D. 1482, David was prior.
A.D. 1524, Edmund Butler was prior, and the last who presided over this venerable establishment. Its property in land consisted of 768 acres, besides twenty messuages, and the income of rectories amounting to £111 16s 8d, or twenty-two marcs, which would in American money exceed $550.
All this property was granted forever to Thomas, earl of Ormond, at the yearly rent of £49 3s 9d. Queen Elizabeth confirmed this grant and remitted the reserved rent.
Athassel is one of the most extensive ruins in the kingdom, and scarcely yielded to any in extent and splendor. The whole work was uniform, regular, and finished in a fine limestone.’

From The Official Illustrated Guide to the Great Southern and Western Railway by George S. Measom (1867):
‘The site was chosen with the usual taste and judgement of “monks of old”; although a few shriveled trees are now all that remains of the woods by which it was formerly encompassed, and of which there is abundant evidence. A gentle, fertilizing and productive river still rolls beside its shattered glories; and the ruins afford ample proof of the vast extent, as well as the singular beauty of the structure, when the “Holy Augustinians” kept state within its walls. To their order may be traced the most elaborate and highly wrought of all the ecclesiastical edifices in Ireland; their abbeys in that country “evincing a style of architectural elegance and grandeur but little inferior to their fabrics in England and on the Continent”.’

From The Parliamentary Gazetteer of Ireland (1846):
‘The ruins of the edifice are still extensive, and indicate its former magnitude and splendor. The choir measured 44 feet by 26; the nave, of the same breadth as the choir and supported by lateral aisles, was externally 117 feet in length; the tower was square and lofty; and the cloisters were extensive. A tolerable view of the ruins from the north-west, and exhibiting the dilapidated tower, the roofless nave, the cloisters and a roofless chapel in the south-west corner, is given by Dr. Ledwich in his Antiquaries of Ireland. “We cannot,” says that antiquary, “behold the numerous arches, walls, windows, and heaps of masonry promiscuously mixed in one common ruin, without saying with Ovid: Omnia sunt hominum tenui pendentia filo: Et subito casu, quæ valuere, ruunt.’ [All things human hang by a slender thread: that which seemed to stand strong, suddenly falls into ruin]