Claudius Silvanus, born in Gaul, is the son of Bonitus, a Frankish general who had supported Constantine I against Licinius.
He held the rank of tribune in 351 and was recorded as having defected to Emperor Constantius II at the Battle of Mursa Major, after initially supporting the usurper Magnentius.
Silvanus had eventually risen to the rank of magister militum: Constantius in 352-353 had entrusted him with the task of driving the Germanic tribes attacking Gaul back beyond the Rhine, a task Silvanus fulfilled by bribing the Germans with the taxes he had collected, thus ending a ten-month Frankish siege of Cologne.
Some of the courtiers of Constantius have now smanaged to persuade him that Silvanus is planning to seize power.
The praetorian prefect Lampadius and the ex-treasurer of the Privy Purse, Eusebius, according to Ammianus had used a sponge to alter a letter sent by Silvanus to his friends in Rome.
The fake letter suggested that Silvanus was attempting to win support within the city for a coup.
Constantius's camarilla, with the exception of the Frankish generals Malarich and Mallobaudes, is uniformly against Silvanus, and the courtiers Apodemius and Dynamius compose additional fake letters.
Constantius holds a trial in which Silvanus' allies are successful in defeating the spurious charges against the general.
Silvanus, unaware of the success of his supporters, on August 11, 355, responds to the threat of condemnation and execution by actually proclaiming himself emperor in Colonia Agrippina (modern Cologne).
Constantius, who is in Milan, orders Silvanus to come to him, and names Ursicinus to take over Silvanus' post.
Ursicinus is himself at odds with Constantius's camarilla and Silvanus no doubt trusts the veteran general.
The letter that Ursicinus had given to Silvanus does not indicate that Constantius already knew of Silvanus' bid for power, so Silvanus considers himself safe.
Ursicinus, however, arranges the murder of Silvanus by co-opting some of the rebel soldiers, who kill the usurper's guard, drag Silvanus from the Christian church in which he is worshiping, and hack him to death.
