IMPERIAL ROME NEVER REALLY solved the problem of orderly succession to power. The "normal" pattern of inheritance in a monarchy is an elderly ruler replaced after his natural death by a well-qualified adult son. For Rome,this was an exception, not a rule.

Officially, an emperor had to be recognized by the Senate to be considered "legitimate", but the increasingly powerless senators were often willing to stamp their approval on anyone who had the cash to bribe or the muscleto threaten them.

Many emperors died by suicide or by violence, often at the hands of their own troops or palace retainers. A few fell in battle. The unfortunate Carus (ruled 282 - 283) supposedly was struck by lighting, although this maybe a cover story for assassination.

During the chaotic third century, more than 30 men simply declared themselves emperor, or were proclaimed as such by their legions. One of the first things a claimant needed to do was issue coins-to symbolize hisauthority, publicize his image, and, of course, pay his troops. It is a tribute to the remarkable efficiency of Roman mints that even rulers who held power for a few weeks were able to get coins bearing their image andtitles into circulation. The coins of these "usurpers" are some of the rarest - and ugliest - Roman coins ever minted.

To read the complete article, see:
Imperial Wannabes: The Ancient Coinage of Roman Usurpers(https://coinweek.com/ancient-coins/imperial-wannabes-the-ancient-coinage-of-roman-usurpers/)