Weld considers it likely that the fortress was built from an English plan, and remarks on the apparent absence of patching, it all seeming to date from the same period.
Robert d’Ufford, Lord Justice of Ireland, began to erect the castle in 1268, while Hugh, King of Connaught, was too ill to prevent such encroachment on his territory. Some authorities state a fortress existed here prior to this time. During 1270-72 there are numerous accounts of payments for building and fortifying the stronghold.
In 1275-76 is an entry of payment to Brother Maurice, Bishop of Elphin, for the site that had been used, and which appears to have been Church property.
The castle is said to have been razed by O’Conor in 1272, but the word “broken” used in the Book of Howth seems to be nearer the truth, as four years later the Irish again seized it by scaling ladders and overthrew the English garrison.
In Weld’s Statistical Survey he gives an amusing account of the contradictions which obscure the early history of the stronghold, and from which it appears impossible to gather the true facts at this distant period.
In 1277 Sir Robert d’Ufford was again Lord Juctice, and with Thomas de Clare, Maurice Fitz-Maurice and all their forces was hemmed in by the Irish in the Slievebawn Mountains. They were only released on the condition that Roscommon Castle was surrendered to the O’Conors.
It is also chronicled that Hugh O’Conor destroyed it in this year and that it was rebuilt by Maurice Fitz-Maurice.
At any rate it seems again to have been in English possession in 1282-83, as there are entries regarding payment for its fortifications, and a grant to the Prior and Convent of St. Coman of a right to water their animals for ever at the lake under the castle. This sheet of water, which was called Loch-na-nean, or “the lake of birds,” has now entirely disappeared.
The names of numerous constables of the castle are mentioned in the State Documents.
In 1290 the castle was garrisoned by Welshmen, and the townspeople were in great distress because of the constables and bailiffs preying upon them. The King issued an order that nothing must be taken without consent and payment.