In May 1738 at the age of 9 he was nominally enrolled in the musketeers, as his aristocratic family chose military over civil service for him. He rose through the ranks, eventually joining the (fr.) as a lieutenant in 1746. That same year he married Marie-Sophie, granddaughter of the celebrated Marshal Château-Renault. His regiment was called to serve in the War of the Austrian Succession. D'Estaing served as aide-de-camp to Marshal Saxe throughout the Flanders campaigns of 1746–48. During these years he was promoted to colonel in command of Regiment de Rouergue, and was wounded at the 1748 Siege of Maastricht.