In 1690 O'Gara commanded the Jacobite garrison at Jamestown in County Leitrim, repulsing an advance by a larger force of Williamite troops under James Douglas.
Another Mág Samhradháin was a captain in the infantry regiment of Colonel Henry FitzJames (1st Duke of Albemarle in the Jacobite peerage) under the command of Lieutenant-Colonel Thomas Corbet.
During their prosperous days, a stately castle reared its head, adjoining to the town, and was the abode of the Barons, but it was dismantled by order of Oliver Cromwell, and now lies in ruins.
The revolution which succeeded, prevented my grandfather from reaping any benefit from James's gracious intentions, and he had the mortification to see the estates which had just been granted him, bestowed by William on those who had favoured his cause.
And such was his hapless fate, that bereft of his title and property, he was even obliged to become a tenant of a small part of those lands his ancestors had for many centuries been Lords of.
My father succeeded my grandfather in his farm; but so inexperienced were the natives of that part of Ireland, then, in the art of agriculture; or so indolent was he, and so loath to abate of that hospitality to which he had always been accustomed, that he gave up the lease of an estate, as not being worth holding, that now brings in to its present possessor, the Earl of Tyrone, between seven and eight hundred a year".
[4][5] In the same work Major Edward also refers to Bryan's brother Captain Donell Mág Samhradháin- On my first arrival at Prague, I had given out, with truth, that I was a grandson of Colonel Bryan M'Gauran, who had followed the fortunes of James King of England, and served in his army — and as Hugh, the son of Captain Daniel M'Gauran, my great uncle, had married the lady first mentioned (Mary O'Donnell), my cousin, his son, was consequently cousin-german to the two Generals, and had always reported himself to be a grandson of Colonel Bryan M'Gauran, in order to give himself the greater consequence; it was therefore concluded that I was this gentleman's brother.