René served in the army of Italy and the army of Flanders in the War of the Austrian Succession, and was Mestre de Camp (proprietary colonel) of the regiment of Berry cavalry at the Battle of Fontenoy (10 May 1745), where he was promoted to Brigadier. He was associated with his father in his work of reorganizing the army, was made Inspector of Cavalry and Dragoons (1749), and succeeded his father as Master of Horse (1752). He introduced English horses into France.[1][clarification needed]
He followed his father into exile on their country estate at Château des Ormes (1763), and in the last years of the reign of Louis XV. sided with the malcontents headed by Duke of Choiseul. However, upon the rupture with England he, rejoined the service of the King in 1775. He was appointed as Inspector of the Seaboard, and was responsible for putting the roadstead of the island of Aix into a state of defence during the American War of Independence.
He contracted malaria while attempting to drain the marshes of Rochefort, and died at Château des Ormes on 18 September 1782.[1]