He and Saint-Just were made the Convention's commissioners to the armies and set out on this mission to eastern France, where he reorganized the army after its reverses at Wissembourg. Saint-Just and Le Bas were also later sent to reorganize the armée du Nord by the Committee of Public Safety in the face of an attempted return by Austrian forces after Wattignies - it was this reorganisation that made possible the victory at Fleurus. Since 1 June he was appointed as the director of the "École de Mars", formerly known as the École Militaire.