Edward Gibbon thinks fit to assume that these events took place after the defeat and capture of Valerian (a. d. 260) ; but our only authority expressly asserts, that the death of the usurper happened while the emperor was upon his march to the East (a. d. 258 or 259); and by that statement we must, in the absence of all other evidence, be content to abide. The medals published by Groltzius and Mediobarbus are rejected by Numismatics as unquestionably spurious.