La Martillière commanded the artillery park of the Army of the Rhine (1797) and successively the Army of Mayence (1798) and the Army of the Danube, 1799. Following the reorganization of the Army of the Danube in April 1799, he was attached to André Masséna's Army of Helvetia. He participated in the Ostrach, Stockach, and Zurich, after which he was transferred to northern Italy, where he was at the Battle of Novi and the Battle of Marengo.