The ancient world never quite figured out the question of succession. The Roman Empire, like most in antiquity, had traditionally passed the throne from father to son, keeping control of the state in the hands of a small group of families. The great weakness of this system was that if the dynasty failed to produce an heir, the empire would convulse in a bloody struggle until the strongest contender prevailed. Whatever successive emperors might say about their divine right, the truth was that their legitimacy rested on physical strength, superior brains, or a well-placed assassination. Only in the written constitutions of the Enlightenment would political regimes find a solution to this basic instability. Without it, every reign was reduced at its core to the principle of survival of the fittest—or, as Augustus, wrapped up in the cloak of the republic, had more eloquently put it,
Rome never really figured out a stable means of succession, but it did come close. Two centuries before Diocletian, in what must have seemed an idyllic golden age to the war-torn empire of his day, a succession of brilliant, childless rulers had handpicked the most capable of their subjects and adopted them as heirs. For nearly a hundred years, the throne passed from one gifted ruler to the next, overseeing the high-water mark of Roman power and prestige, and offering a glimpse of what could be accomplished when qualifications to high office were based on merit instead of blood. But this oasis of good government was only due to the fact that none of the adoptive emperors had sons of their own, and in the end heredity proved to be its Achilles’ heel. Marcus Aurelius, the last of the “adoptive” emperors, had thirteen children, and when he died he left the empire to his aptly named son Commodus. Drunk with power and completely unfit to rule, the new emperor convinced himself that he was a reincarnation of Hercules, took the title
Diocletian’s final announcement, therefore, was a revolution nearly fifteen centuries ahead of its time. This was not simply the abdication of a tired old man; it was a full-blown attempt at a constitutional solution to the question of succession. Both he and Maximian would be stepping down at the same time; their respective Caesars, Galerius and Constantius the Pale, would become the senior emperors, appoint their own Caesars, and complete the smooth transfer of power. Not only would this ensure a clean, orderly succession without the horrors of a civil war, it would also provide the empire with experienced, capable rulers. No man could become Augustus without first having proven himself as a Caesar.
Laying down the crown and scepter, Diocletian renounced his power and happily settled down to plant cabbages at his palatial estate in Salonae, on the Adriatic coast.* His contemporaries hardly knew what to do with a retired god, and history has proved in its own way just as mystified about his legacy. He ended chaos and restored stability—perhaps enough to have earned the title of a second Augustus—but had the misfortune to be eclipsed—in every sense of the word—by the man who nineteen years later rose to power. Diocletian had cut the Roman Empire free from the moorings of its past, but the future lay with Constantine the Great.
*Ronald Mellor,
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CONSTANTINE AND THE CHURCH ASCENDANT
—TERTULLIAN
The tetrarchy deserved to survive a good deal longer than it did. There was, however, a rich historical irony in the way it collapsed, since Diocletian had gotten the idea from Roman history itself.