THE NEW LEGITIMATION OF IMPERIAL POWER

When Diocletian rose to the imperial dignity after the assassination of Numerian and after rapidly ridding himself of Carinus, he possibly adopted – and certainly appointed as Caesar and shortly after as Augustus – Maximian, an old comrade in arms and like himself a man of humble origins, whom he sent to control the west. The new system of government was thus diarchic and as such had precedents in the history of the third century. But what was now being given some form of official sanction was a territorial partition of duties between the two Augusti. A few years later, in 293, two other soldiers, Constantius Chlorus and Maximianus Galerius, were raised to the purple as Caesars. The diarchy was transformed into a tetrarchy.

As a system the new division of power had a certain complexity. While to a certain extent it endeavoured to recall the methods of legitimating imperial authority peculiar to the adoptive empire, at the same time it also retained the traditional dynastic ideology. Relations between the tetrarchs were thus cemented by matrimonial links: Galerius with Diocletian's daughter, Constantius with Maximian's daughter. Even in Diocletian's case the fact that he had no male offspring of his own must surely have had some influence on his decisions. Within the imperial college, Diocletian's position remained one of undisputed pre-eminence. Most likely the new system was not, as some have claimed (both in the past and even recently), the product of an overall design in which every element was pre-arranged, but instead an empirical response to the problems of the empire.