As a boy, Berthier was instructed in the military art by his father, an officer of the "Corps de genie" (Engineer Corps). At the age of seventeen, he entered the army, serving successively in the staff, the engineers, and the Prince of Lambesc's Royal Allemand-Dragoon Regiment. In 1780, Berthier went to North America with General Rochambeau, and on his return, having attained the rank of colonel, he was employed in various staff posts and in a military mission to Prussia. During the French Revolution, as chief of staff of the Versailles National Guard, he protected the aunts of Louis XVI from popular violence, and aided their escape in 1791.