He was still a subaltern at the outbreak of the Revolution, becoming captain in 1791. His ability as a military engineer was recognized in the campaigns of 1792 and 1793. In the following year he won distinction in various actions and was promoted successively chef de bataillon and colonel. He was chief of engineers at the siege of Mainz in 1793, after which he was sent to Italy. He there commanded the positions and lines of advance of the army of Bonaparte. He was promoted brigadier-general before the close of the campaign, and was subsequently employed in fortifying the new Rhine frontier of France.