Death of Owen McCarthy, Esq., age 84, near Blarney, Co. Cork, ‘commonly called Master-na-Mona, or Lord or Master of the Preceptory of Moran, in this county. He was the last of that ancient and respectable family, except an only son, no Governor of Miranda, and Colonel of 4th Regiment of Horse in the Portuguese service, where by his valour, he was promoted in a sovereign clime to honours, which he was rendered incapable of enjoying in his native country from the severity of Penal Laws. The deceased had fifteen brothers, thirteen of whom, on said account, emigrated for bread after losing their estates in this Kingdom, and were promoted to high ranks in the different armies of France, Spain, Portugal and Germany. From the Hibernian Chronicle 6th December 1790.

http://corkgen.org/publicgenealogy/cork/potpourri/corkancestors.com/Deathsmarriages2.htm

Many of the old Gaelic and Catholic landed families entered foreign service n France, Spain and Austria. Some who achieved high office were enrolled in the nobility of their adopted countries. They were sometime obliged to compile their genealogies as a condition of such entry. People such as the Chevalier Thomas O’Gorman in late 18th century France were among those who performed this function.

An example of this is that of Count O’Reilly of the Cavan/Breffni family:

https://durrushistory.wordpress.com/2014/03/27/discovery-of-lost-vellum-manuscript-documenting-oreillys-genealogy-of-breffni-cavan-over-1000-years-in-munich-2008-irish-presence-in-cuba-18th-century-and-irish-named-street-escape-castro-emba/