[3] Writing in 1826, the British topographer and novelist James Norris Brewer states that the Gilbertine Abbey was founded in 1218, on the site of a monastery that had stood there from before the year 700.

[citation needed] In the period of decline for the colony following the Bruce invasion and the Black Death, the lands around Ballymore fell to the hands of a locally based Hiberno-Norman family of Dalton.

[citation needed] By about 1600, Ballymore had become the property of Sir Francis Shaen, an Elizabethan soldier, who had been involved in the plundering of Multyfarnham Abbey.

Their garrison was located beside Lough Seudy, and divided from the mainland by "a deep and large graff, with ramparts of earth and bulwarks: the ditch was carried so low as to receive three or four feet of the stagnant water of the lake, over which was by a draw-bridge the entry into the fort; this was the chief fortress of this county".

James left Ireland after defeat at the Battle of the Boyne in 1690, but the successful resistance at the Siege of Limerick gave the Irish Jacobites time.

Prior to that, in late 1690 and early 1691, while the main armies went into winter quarters, an area east of the Shannon became a zone of contention which was ruinous to the local population caught between the two forces.

The Williamites established small garrisons around which irregular Irish forces, rapparees, and raiding troops from the Jacobite positions operated in small-scale actions.

With a large force of mounted and infantry troops, de Ginkell left Mullingar in early June for Ballymore, where, in a fort on the shores of Lough Seudy, a thousand adherents of James II were encamped.

[8] "The [fort], which stands on the verge of Lough Seudy, was defenceless towards the lake, and as the besiegers not only battered it with their artillery on the land side, but approached it on that of the water by boats, the governor, Colonel Ulick Burke deemed it right to surrender on the following day".

An account from an eyewitness [16] from the Williamite camp reported that the fort was "haunted by wretched people in the lowest stage of suffering, from the famine caused by the waste of both parties."

He reported that while the English army had supplies, they "could afford nothing to the crowd of forlorn and famishing outcasts whom danger collected around the camp; to these, so dreadful was their destitution that a morsel of garbage was a feast, and they flocked as ravens round the putrifying and blackened carcasses of dead horses which lay rotting in the summer sun".

It comprises a six-bay nave with an attached three-stage tower on square-plan to the north with a slated pyramidal roof, flanked to the east and west by advanced gable-fronted bays containing the main entrances.

It comprises a three-bay hall to the east and a three-stage tower on square plan to the west end, having crow-stepped parapets and corner pinnacles.