Victor François de Montchenu came from one of the oldest families in the Dauphiné, and one long devoted to military service.
He was admitted to the Ecole des chevaux-légers as a child and in 1775 became sous-lieutenant of the régiment d'infanterie du Roi (King's Infantry Regiment), at a time when officer ranks were reserved for sons of the noble families.
He was a captain in this corps during the Nancy affair, finding himself beside André Désilles when the latter died by throwing himself in front of a cannon in a vain hope of stopping the battle between the mutineers and the troops of de Bouillé.
Consistently monarchist, Montchenu quickly decided in 1792 that the royalist cause was irrevocably separated from the nation's cause and left France to join the armée des Princes, serving in it as aide-de-camp to général Livarot.
In March 1793 he assisted in the defence of Maestricht against Charles François Dumouriez's force and served as an aide-major in the 1794-95 campaigns in the régiment de Broglie in the pay of England.