He was from the younger branch of the Lomenie Flavignac family originating in Limousin, which became in the seventeenth century the house of Brienne. Louis-Marie-Athanasius was the younger brother of Cardinal Etienne-Charles de Lomenie de Brienne, Minister of Louis XVI. As Lieutenant General of the armies of the king, he commanded the Royal regiment of Artois from 1747 to 1762. Appointed Secretary of State for War from 1787 to 1788, he was guillotined on 21 Floreal Year II (May 10, 1794) with four other members of his family and Élisabeth de France.