The agentes in rebus (, or , magistrianoí, 'magister's men') were the late Roman imperial courier service and general agents of the central government from the 4th to the 7th centuries. History The exact date of their institution is unknown. They are first mentioned in 319, but may date to Diocletian's reforms in the late 3rd century, when they replaced the earlier and much-detested frumentarii. The central imperial administration still needed couriers, and the agentes in rebus filled this role. Originally they acted as dispatch carriers, but eventually assumed a variety of duties—the title itself translates as "Those Active in Matters". They fell under the jurisdiction of the magister officiorum (Master of the Offices), hence their alternate Greek name of magistrianoi. They were eventually abolished sometime in the early 8th century, as most of the magisters functions were taken over by the logothetēs tou dromou. The last reference to an agens comes in the chronicle of Theophanes the Confessor, where the magistrianos Paul is recorded as having been sent on an embassy in 678. Organization and function The agentes in rebus were formed into a schola of the palace, and in common with other public services of the Dominate, their service was militarized, and considered a militia. Indeed, the agentes were divided into five ranks, taken from the junior cavalry officers: equites, circitores, biarchi, centenarii and ducenarii. Two were appointed to each province in 357, one in 395 and more again after 412. Each member of the agentes in rebus was normally promoted into other branches of the government. The Code of Justinian notes furthermore that the agentes enjoyed immunity from prosecution both civil and criminal, unless otherwise sanctioned by the Master of Offices. Senior agentes were regularly appointed to the post of princeps officii of the praetorian prefectures, the urban prefectures and the dioeceses, thus exercising control over these departments' bureaucracy and reducing its independence. As for their function, the 6th-century historian Procopius notes in his Secret History: As the service handling communications and communications systems within the Empire, their duties included the supervision of the roads and inns of the cursus publicus (public postal system), the carrying of letters, or verifying that a traveller was carrying the correct warrant (evectio) while using the cursus. Further duties assigned to the agentes included the role of customs officers, the supervision of public works and the billeting of soldiers. They were