From the creation of the province of Numidia under Septimus Severus to Gallienus's reform, in 262, which involved the replacement of the legatus propraetor clarissimus by an equestrian governor, the province was ruled by a senator, himself a former praetor. The latter, in his capacity as a commanding officer (of the legio tertia Augusta), had a military staff in Lambaesis (which had become the capital of the new province), and in his capacity as a governor, had an officium. How did the provincial administration actually work, especially in the absence of the third legio when this corps was dissolved, between 238 and 253/256 ? This is the subject of the present study. Following Gallienus's reform, it had appeared that the first equestrian r...