Les jeux d’alliances des tétrarques en 307-309 et l’élévation de Constantin au rang d’Auguste

An interpretative study of a group of inscriptions, corroborated by numismatic and papyrological data, throws light on some aspects of the crisis of the imperial college that have been omitted by the litterary tradition and enables to propose a more precise view of the date, circumstances and immediate consequences of Constantine’s elevation to the rank of Augustus. Thus, two milliaries from Cilicia which we date in november 307 celebrate a college made up of the Augusti Maximian and Galerius and the Caesars Maximinus and Constantine. In the same way as the contemporary coins and papyri, they reveal several features of the politics displayed by Maximin between 307 and 309, among which especially his obvious opposition to Galerius following the later’s refusal to promote him Augustus in place of Severus who died on 16 september 307, equally his unfailing support to Maximian’s come back to the ruling team as first Augustus and the political alliance formed in november 307 with Maximian and Constantine. The counterpart of the milliaries from Cilicia is to be found in the coins struck by Constantine in honour of the same imperial college, which we date in autumn 307, as well as the proclamation in Gaul of Maximian and Constantine as consuls, after Severus’ death. Since they style Constantine Caesar in november 307, the Cilician milliaries afford a new terminus post quem for his promotion to the rank of Augustus and wedding with Fausta, which we consequently place in december, not september, 307. Furthermore, the alliance of Maximinus they are ascertaining had a remarkable impact, both political and strategical, on these two events, in the context of the failure of Galerius’ campaign in Italy. The analysis of Constantine Augustus’ coinage discloses not only his quest for recognition of his rank, but also his attempt at restoring the cohesion of Empire by striking at the beginning of 308 in the name of a college fitting with the realities of the moment, including the four Augusti Maximian, Galerius, himself and the usurpator in Rome Maxentius, as well as the Caesar Maximinus. The rejection of this project gave way to the apex of the crisis, when Constantine struck only in his own and Maximian’s name. For his own, Galerius no longer recognized Constantine’s legitimacy from autumn 307, followed by Maximinus from the beginning of 308. This is confirmed by the imperial epistula to Heraclea Sintica promulgated only in the names of Galerius and Maximinus, thus to be dated in the first months of 308. From that reconstruction, the seriousness of the 307-308 crisis invites us to reconsider the effects of the meeting held at Carnuntum in november 308 and highlights Constantine’s political qualities, the one among all those emperors who was ever able to draw benefits from this struggle for power, while strenghtening his own.