He became a sergeant in the 1st Arsenal battalion and in 1793 moved to the artillery at La Fère, assisting in the sieges of Landrecies, Le Quesnoy and Valenciennes.

He became aide-de-camp to Marshal Berthier in 1800, a post he retained until 1812 and in which he took an active part in practically all of the Napoleonic campaigns.

He was promoted to full captain after Marengo and chef de bataillon after Austerlitz, also becoming a knight of the Légion d'honneur and a colonel at the Siege of Saragossa.

Lejeune was fascinated by the possibilities of the new method and whilst there he made the drawing on stone of his famous Cossack (printed by C. and ~f.

Freed in March 1813, Lejeune was then sent to the Illyrian provinces, before rejoining the army under the orders of Marshal Oudinot, becoming his chief of staff.

In 1837 he became director of the École des beaux-arts et de l’industrie in Toulouse, a city of which he became mayor in 1841 and in which he died of a heart attack aged 73.

"[1] When his battle-pictures were shown at the Egyptian Hall in London, a rail had to be put up to protect them from the eager crowds of sightseers.

He also produced several studies of uniforms in the French Imperial Army, such as those of the lancers of Berg under Murat and of Berthier's aides-de-camp.