At first destined for a career as an architect (for which he showed a marked disposition), he fought in his first battles in 1788 as a volunteer in the "Canaris" (after its uniform's colour) cavalry regiment during the Brabant Revolution. He became a lieutenant colonel in that unit in November 1789. After the revolution was stopped in 1790, he fled and offered the First French Republic his services, commanding a battalion of the Belgian Legion, fighting at Jemappes and rising to général de brigade in 1793 after his defence of the approaches to Lille against the young comte de Bouillé.