Lactantius

“ Galerius having resolved by permanent taxes to devour the empire, soared to such extravagance in folly, as not to allow an exemption from that thraldom even to the Roman people. Tax-gatherers therefore were appointed to go to Rome, and make out lists of the citizens. Much about the same time Galerius had reduced the Pretorian Guards. There remained at Rome a few soldiers of that body, who, profiting of the opportunity, put some magistrates to death, and, with the acquiescence of the tumultuary populace, clothed Maxentius in the imperial purple. ”

“ To his father, who since his abdication resided in Campania, he sent the purple, and saluted him again Augustus. Maximian, given to change, eagerly resumed that purple of which he had unwillingly divested himself. ”