Moreaux served in the campaign to capture the Fortress of Mainz which ended in failure at the Siege of Mainz. On 30 July 1793 he received promotion to the rank of general of division. He was appointed to command the Corps of the Vosges which occupied the Electorate of Trier. On 20 August, three battalions, six squadrons and 10 guns belonging to the Corps of the Vosges were defeated near the Lines of Weissenburg by a Coalition force numbering five battalions, six companies, 13 squadrons and 12 guns. The French commander Louis-Théobald Ihler was killed in the action. Out of 3,000 soldiers, the French lost 103 men and five guns captured plus an unknown number of killed and wounded. The Coalition sustained 147 casualties.