Diocletian: Forging the Byzantine Empire.

by Pat Lowinger

Historians are often overly concerned with dates- which is understandable given the nature of their collective field of study.  Dates help to temporally organize significant events and eras into convenient timelines; facilitating the use of descriptive terminology such as Geometric, Archaic, Classical and Imperial.  One of the more problematic but commonly used terms is ‘Byzantine.’ 

A Tradition of Divided Power

The division of power with the Roman Empire was nothing new.  With roots as far back as the Republic, authority and power (particularly power involving the military) was often divided between appointees of competing camps.  In the Republican era, the division of power was ascribed between consuls, who during their one-year term(s) of service, alternated monthly as the reigning head of state and as the supreme commander(s) of the military during times of war.  From these Republican ideals grew other traditions which ascribed the division(s) of power within the Empire.  In particular, the First and Second Triumvirates- dedicated to division of military and political power under the auspices of ensuring stability within the Late Republic.

Diocletian as Jupiter of the East


Map depicting the division(s) of the Roman Empire under the reign of the Tetrarchs.

Beginning with the reign of Maximinus I in 235 AD through reign of Carinus ending in 285 AD- the Empire had seen rise/fall of 22-26 emperors within a 50 year period.  This Crisis of the Third Century saw the near destruction of the Empire from internal and external threats. [1] While some of these emperors, like Aurelian, were able to consolidate enough military and political power to prevent the Empire’s total collapse, the future was certainly grim.  Numerous civil wars and uprisings drained the frontier garrisons which were bypassed or overwhelmed by Germanic invaders.  Eventually, Rome’s legions defeated the Vandals and Visigoths in a series of costly military campaigns.  The Empire’s coffers and manpower were at critically low levels.

After securing his position as Emperor following the death of the Emperor Carinus, Diocletian could have, and in all likelihood should have become just another in a long list of short-reigned Emperors.  Despite the still festering wounds of civil war, Diocletian enacted a general amnesty (clementia), guaranteeing the lands, titles and offices of recent belligerents- upon a simple oath of loyalty.  Their status secure, the Empire’s aristocracy largely capitulated to Diocletian’s rule, while the urban and rural poor largely welcomed it.   Diocletian initially followed the earlier Roman convention of divided rule (east and west), by the appointment of Maximian as co-Emperor in 286 AD.  With each


Gold Aureus c. 294 CE, minted at Nicomedia. Obverse (top)- “Diocletian the happy, pious Emperor.” Reverse (under)- Jupiter holding thunderbolt, “Jupiter the Preserver.”  American Numismatic Society ID# 1955.191.4.

Emperor appointing their own successor who would control their own (4) territories within the Empire- the ‘Tetrarchy’ was formed. [2] Whether Diocletian resigned himself to this division of power out of tradition, a practical need for more centralized authority within the various provinces of the Empire, the trust which existed between himself and Maximian and/or all of these reasons the effect was the stabilization of the Empire.

In effect, Diocletian had formally divided the Empire into east and west, each Emperor (Augustus) and that Emperor’s chosen successor (Caesar) ruling large swathes of the Empire independently from each other.  Stability of the larger ‘Empire’ was rooted in mutual cooperation between each of the four rulers.  The Tetrarchy would last for 19 years.  During this period Diocletian and the other Tetrarchs were able to stabilize the military frontier of the Empire, quell internal unrest and enact economic reforms designed to stabilize the Empire’s economy.  By establishing the seat of his rule in Nicomedia (in the northwestern portion of Anatolia), Diocletian symbolically and in  practice transferred the seat of Imperial rule to the east.  While Rome, under Maximian remained the seat of power in the west, his status as Hercules to Diocletian’s Jupiter, cemented the transfer of power outside of Italy, as well as affirming Diocletian’s primacy. [3]  This realignment of power preceded the founding of Constantinople by 38 years- a fact this is often ignored or underdeveloped by too many modern historians analyzing the period.  From this point forward, imperial power would be concentrated in the east, in effect re-centering the Roman world.


Whether Diocletian was a visionary or realist can be debated.  He was an experienced military and political leader. Diocletian, born in Illyria of strong Illyrian stock, appears to have been less impressed by the status of Italy than his predecessors.  He also realized the importance of securing Asia Minor and the vital trade routes which passed through it.  By the establishment of his imperial residence and administrative headquarters at Nicomedia, Diocletian shifted the loci of imperial power eastward.  While Rome may have retained a symbolic link to the past glories of the Empire, it was no longer the epicenter of Roman dominion.  “The beginning of Byzantine history can be traced back to the Roman Empire as it emerged from the crisis of the third century.  The economic difficulties of this period had had particularly disastrous effects on the western half of the Empire.  The east had greater powers of resistance-a factor which afforded future development and accounted for the Byzantinizing of the Roman Empire.”[4]  Perhaps, Diocletian himself could best be described as the first Byzantine Emperor…


Sculpture of the Tetrarchy (material: porphyry) dated to c. 300 CE.  Originating from Constantinople – it was taken to Venice during the early 13th century CE.


Glay, Marcel Le, Jean-Louis Voisin, and Yann Le Bohec. A History of Rome. 4th ed. Cambridge, MA, USA: Blackwell, 2009.

Ostrogorski, Georgije. History of the Byzantine State. New Brunswick, NJ: Rutgers University Press, 1969.


[1] Marcel Le Glay, Jean-Louis Voisin, and Yann Le Bohec, A History of Rome, 4th ed. (Cambridge, MA, USA: Blackwell, 2009), 459-462.

[2 &3] ibid., 473.

[4] Georgije Ostrogorski, History of the Byzantine State (New Brunswick, NJ: Rutgers University Press, 1969), 29.

About Patrick Lowinger

Patrick Lowinger holds a M.A. in Ancient and Classical History from American Military University (AMU) and B.S. in Microbiology (1993) from California State University, Long Beach.
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