Carino Augusto e le usurpazioni incrociate di Diocleziano e di Sabinus Iulianus (284/285)

Carinus Augustus and the crossed usurpations of Diocletian and Sabinus Iulianus (284/285) · Between the end of the year 284 and the spring of 285 there were two simultaneous usurpations, both to the detriment of the legitimate Augustus, Carinus : the most famous and fortunate one of Diocletian, commander of the protectores of the deceased Numerian, in Nicomedia, and the less known and failed one of Sabinus Iulianus, praetorian prefect of Carinus, in northern Italy. The Excerpta de Insidiis fragment extracted from the Historia chronikè by John of Antioch, taken from Zosimus (Ioh. Ant. fr. 246 Roberto = fhg iv, p. 601, fr. 163 Müller = Zos. i 73, 1-3) describes two independent and simultaneous usurpations (November 284). The geographical and chronological reconstruction of the events makes it possible to establish that the praetorian prefect of Carinus, Sabinus Iulianus, usurped the purple when the news of Numerian’s death, not of Diocletian’s acclamation, arrived in Italy, while Diocletian was elevated by another army probably at the same time in Nicomedia. The weakness of the two armies of the two usurpers, the mutual mistrust, the monocratic nature of the imperial power prevented an effective agreement, even if attempted. Carinus, legitimate Augustus and skilful general, came down from Gaul with a great army and defeated first Sabinus Iulianus in Verona (March/April 285 ?), then Diocletian in Margum in Mesia (June 285 ?). The lack of synergy between the usurpers Sabinus Iulianus and Diocletian favored the victories on the field by Carinus. But the crisis of the political program of Carus and Carinus, based on expensive campaigns and on a rigid family closure, produced the assassination of Carinus, victorious at Margum, and the unexpected affirmation of Diocletian, defeated in the field, and author of an inevitable and significant amnesty. The officers alongside Carinus and those who supported the two usurpers seem to have aimed to oppose the dynastic system. This was the policy of Diocletian and the Tetrarchs : sharing imperial power with skilful experienced commanders, no privilege for blood relatives.