Craig Caldwell
The usurpation of the general Vetranio in 350 was an outlier: it was neither a successful seizure of the purple that produced a new dynasty, nor a spectacular failure that resulted in the bloody demise of its adherents. While this would-be emperor has attracted scholarly attention as a participant in the civil wars fought and won by Constantius II in 350–53, Vetranio was a uniquely Danubian solution to the sudden apparent weakness of the Constantinian dynasty (Drinkwater 2000, Bleckmann 1994). Close attention to Vetranio’s ten-month reign can reveal how soldiers and officials in one region responded to the threatened collapse of the order and prosperity represented by Constantine and his sons, and thus we may discern some of the limits of dynastic legitimacy in the mid-fourth century.
Vetranio has confused modern scholars far more than his contemporaries, who reduced him to the caricature of a rustic old soldier from upper Moesia (now Serbia and Macedonia). Only the derisive outline of Vetranio’s usurpation survives in various late antique historians, but his coinage provides us with the watchwords of his rhetorical strategy (Dearn 2003). His rule was an extension of Constantine’s victory at the Milvian Bridge, from the labarum standard and legend HOC SIGNO VICTOR ERIS on his bronze coins to his association with Constantine’s daughter Constantina. The scholarly stumbling block has been whether he even deserves mention as a usurper in light of his loyalty to the sons of Constantine: did he ever intend to rule independently of Constantius II, who ended Vetranio’s reign with a speech to his troops at Naissus on Christmas Day?
The missing dimension of Vetranio lies in his origin in the same region where he served as magister peditum and then became emperor. Against the dismissal of his Danubian affinity, we should instead consider him as a native son of the Balkan provinces who realized the peril that the events of 350 represented (Mócsy 1974). Following the murder of Constans by his general Magnentius, the great Roman armies of the Rhine and the East were converging on Illyricum to fight a ruinous civil war. The Roman name of the year epitomizes the chaotic situation, as imperial officials dated their correspondence with references to the consuls of 349, Limenus and Catullinus. In that context, the presence in Sirmium of one of Constantine’s relatives, the praetorian prefect Vulcacius Rufinus, was insufficient to rally the soldiers to support Constantius II. The Danubian army acclaimed Vetranio as emperor because he was one of them: he was legitimate enough since he received the imperial diadem from Constantina, but not a true rival to Constantius in the struggle beyond Illyricum. Between the Julian Alps and the Succi Pass (between modern Sofia and Plovdiv in Bulgaria), Vetranio represented the stability and golden age of Danubian patronage by the Tetrarchy and Constantine, the “savior” of the state as opposed to the Rhine army of Magnentius, who proclaimed himself the “liberator.” Without the financial resources to pay large donatives, Vetranio’s principal currency was the memory of Constantine, whose popularity with the soldiers in a vital region was a decisive advantage in favor of the absent Constantius II.
When Vetranio at last yielded his purple robe upon the arrival of the eastern army in the Balkans, Constantius II is said to have lifted the old man from his knees with an embrace. The nature of Vetranio’s usurpation was evident in Constantius’s affectionate invitation to dinner: that emperor, the last surviving son of Constantine, called the former usurper “father” (Zonar. 13.7). Vetranio showed the utility of a substitute for the ruling dynasty when the limits of its legitimacy appeared in 350.