He was the eldest son of Robért Joseph de Cornaule, marquis de Stainville (1700-1770), and bore in early life the title of comte de Stainville. He entered the army, and during the War of the Austrian Succession served in Bohemia in 1741 and in Italy, where he distinguished himself at the battle of Coni, in 1744. From 1745 until 1748 he was with the army in the Low Countries, being present at the sieges of Mons, Charleroi and Maastricht. He attained the rank of lieutenant-general, and in 1750 married Louise Honorine, daughter of Louis Robért Crozat, marquis du Châtel (d. 1750), who brought her husband her share of the large fortune of her grandfather Antoine Crozat and proved a most devoted wife.