Silvanus (died 7 September 355) was a Roman general of Frankish descent, usurper in Gaul against Emperor Constantius II for 28 days in AD 355. Origin and career Silvanus was born in Gaul, the son of Bonitus, a Laetic Frankish general who had supported Constantine I in the civil war against Licinius. Like so many other Franks of his times, and like his father before him, he was a loyal and thoroughly romanized "barbarian" in the military service of the Empire. By AD 351, he held the rank of tribune and was one of the senior officers who defected to Emperor Constantius II at the Battle of Mursa Major, after initially supporting the usurper Magnentius. An able soldier, Silvanus was eventually promoted to the rank of magister peditum per Gallias, a crucial post, then in AD 352–353, Constantius personally entrusted him with the difficult task of driving the Alamanni tribesmen raiding and looting in Gaul back beyond the Rhine, and restoring the fast eroding Roman authority in the province. This Silvanus fulfilled partly by bribing the Alamanni chieftains with the taxes he had collected, partly by defeating the Alamanni in battle and partly by suppressing the local bagaudae insurrections flaring up again in central and northern Gaul. Trial and usurpation The corrupt coterie of Constantius II managed to persuade the suspicious, paranoid emperor, that Silvanus was planning to seize power. According to Ammianus, the praetorian prefect Lampadius and the ex-treasurer of the privy purse, Eusebius, used a sponge to alter a letter sent by Silvanus to his friends in Rome. The altered letter suggested that Silvanus was attempting to win support within the Senate for a coup. Constantius' court clique, with the exception of fellow Frankish generals Malarich and Mallobaudes, was uniformly against Silvanus. Courtiers Apodemius and Dynamius forged further correspondence that cast doubt on Silvanus' loyalty. Constantius then held a trial where Silvanus' allies were successful in defeating the spurious charges against the general. But Silvanus, unaware of the success of his supporters, responded to the threat of condemnation and execution by actually proclaiming himself emperor on 11 August 355 in Colonia Agrippina (modern Cologne). Late Roman historian Michael Kulikowski has argued that the entire episode was a later invention, created as an excuse to rid Constantius II of Silvanus before he became a threat. His primary basis of this argument is the fact that no coins minted with