In 1720, at the onset of the Great Plague of Marseille, Roze proposed his services to the local authorities, the échevins. Strong with his experience from Greece, he was made General Commissioner for the Rive-Neuve neighbourhood. He established a quarantine by setting up checkpoints, and went as far as building gallows as a deterrence against looters. He also had five large mass graves dug out, converted La Corderie into a field hospital, and organised distribution of humanitarian supply to the population. He furthermore organised supply for the city itself.