He was from a noble family of Derrynane House, County Kerry, Ireland, but because of the Penal Laws (Ireland) of the time, which forbade a Catholic to have any education or profession, he, like many other ambitious young Irishmen, went to the Continent for an education, and remained abroad.

He entered the service of the king of France in the Royal Swedish Regiment (Royal Suédois) in 1761, and in 1769 was transferred to Lord Clare's Regiment of the Irish Brigade (French) and served in Europe and Mauritius until 1778.

He was later appointed Colonel Commander of the Régiment de Salm-Salm [fr], and was created a Chevalier of the Order of Saint Louis.

He also was appointed to a military committee charged with revising French infantry tactics.

[5] He died at Blois, France, at the chateau of his stepdaughter, in July 1833, holding the ranks of General in the French and Colonel in the British army.