He continued to serve as a senior commissary to Napoleon's armies until 1809, when he retired and was made a Senator and later a Count of the Empire.

On graduating he was named Quartermaster - Chief Inspector (Commissaire Inspecteur en chef) to the Army of the Coast.

[6] Villemanzy was told that the bread would feed the army in its march to Philadelphia, but the enemy should be deceived into thinking the plan was to attack Staten Island.

[5] After being posted to Metz and Lunéville Villemanzy was sent to Paris to assist the War Committee of the Constituent Assembly until 1 October 1791.

[8] At the Battle of Metz (1793) the army surgeon Dominique Jean Larrey successfully demonstrated the value of field ambulances.

[8] Villemanzy was exchanged on 2 April 1796 and appointed Commissaire Ordonnateur en chef to the Army of Italy, where he served until September 1798.

After the coup of 18 Brumaire (9 November 1799) in which Napoleon seized power, Villemanzy was made Chief of the Accounting Office at the Ministry of War.

He was appointed Inspecteur général aux revues with the rank of divisional general, and assigned to the Army of the Rhine until the end of 1801.

[5] At the start of the War of the Fourth Coalition in 1806 Villemanzy was replaced as Intendant-General of the Grande Armée by Pierre-Antoine Daru.

[8] After the Treaty of Schönbrunn (14 October 1809) ended the war with Austria, Napoleon made Villemanzy Intendant General of the Grande Armée in Germany.