On 20 January 1798 Pezza was enrolled in the "Reggimento di Messapi", stationed at Fondi, about a dozen miles north of Itri and perhaps a dozen south of the frontier with the Papal States. Pezza rose quickly, becoming a sergeant, probably because he was literate and, as a member of the middle class and a former Royal courier, already familiar with firearms. In November of late 1798 Pezza took part in the disastrous attempt of the Neapolitan Army to oust the French from the Papal States.