Made Duke of Chaulnes and Marshal of France in 1621, he took the name of Marshal Duke of Chaulnes. He served at the Siege of Saint-Jean-d'Angély and the Siege of Montauban. That same year he obtained the government and citadel of Amiens after his brother died. He commanded, with the Marshal de La Force, the army of Picardy, keeping it under royal control, and was made its Governor in 1635. He commanded the same army in 1635 during the Franco-Spanish War, entering Artois, where he razed multiple castles and passed through Grévillers, looting what provisions he could take and burning the rest to deprive the enemy.