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Diocletian, creator of the dominate and tetrarchy, which were to heal raged by the civil war Roman Empire.
Under Creative Commons Attribution license - Under the same conditions, 3.0.

Existing since 27 BCE, principate, gathering power in the hands of the emperor titled princeps (“the first citizen”), with appearances of republican institutions, in the third century CE many times underwent many crises, both internal and external. At the end of this century, the situation began to become more pronounced. The need to defend the state against external attacks, the need to gather forces in one hand in order to maintain the unity of the empire threatened by usurpations and uprisings of the population led to the transformation of the form of rule from the principate to the dominate. This system practically and formally broke with the appearances of the republic and transferred full power to the emperor, “master” (dominus, from whom the name of government came).

Dominate, despite being shaped throughout the entire 3rd century CE, for example by the emperor Aurelian (270 – 275 CE), who was called master and born god (dominus et deus natus) , it was formally established during the reign of Diocletian (284-305 CE) at the end of the century, and continued by Constantine the Great.

Patterns taken from Persia, the Sassanid state, contributed to the formation of this system of government. An eastern court ritual was introduced, characterized by unusual splendor. The emperor ceased to be the first citizen and became a completely independent absolute ruler. The Senate lost its significance and did not play a role at all in the state except maybe in minor matters.


The emperor drew conclusions from the experience of previous decades and carried out a thorough reform of the Roman state. He understood that one person is no longer able to manage such a vast territory. It was not possible to react quickly and effectively in specific situations that occurred at its distant ends. That is why he introduced the system, which was called tetrarchy (from the Greek “rule of four”, “quadruple”; from Latin “quadrumvirate”).

The emperor appointed a co-ordinator with the title of Augustus and entrusted him with the management of the western part of the country. Diocletian remained in the East, but retained authority over all others. Each of the Augustów found a deputy with the title of Caesar. The emperor assumed that after twenty years of rule, Augustów would voluntarily relinquish power and be replaced by Caesars. They will appoint new Caesars who will also become Augustians in the future, which was to continue. This system, however, turned out to be utopian, because after the abdication of Diocletian and his counterpart in the west led to new civil wars.

The first tetrarchs were

  • Diocletian, Augustus of East
  • Galerius, Caesar of East
  • Maximianus, Augustus of West
  • Constantius, Caesar of West

However, major reforms were introduced in administration and the army. First, new offices were created in connection with the reconstruction of the state. The emperor’s closest advisers were members of the imperial council (sacrum consistorium – so-called consistory). In the court, the following positions were introduced:

  • marshal of the Imperial Court (praepositus sacri cubiculi)
  • head of the imperial treasury (comes sacrarum largitionum)
  • imperial property managers (comes rerum privatarum)
  • head of the imperial guard (magister officiorum)
  • head (secretary) of the imperial office (quaestor sacri palatii)

All those officials who replaced the former, functioning during the principate period, received high salaries and were ranked according to the amount of remuneration.

Diocletian also divided provinces into smaller ones, doubling their number from about 50 to about 100 to 120 in the 5th century CE. In this way the emperor weakened the position of governors province and gained better control over them. Several or several smaller provinces, in turn, formed the parent unit, the diocese. At the beginning of the 4th century CE there were 12, then the number increased to 14. In order to manage the doubled number of provinces, the number of central and provincial offices, whose maintenance was one of the main burden of the population, was increased.

Sculpture depicting tetrarchs.
On Creative Commons Attribution license - On these same conditions 3.0.

In order to increase the mobility and mobility of troops at the border, during the reign of Constantine the Great, the army was reorganized into two types. Frontier forces (limitanei) were to take on the first blow of the enemy. On the other hand, the role of the Air Army (comitatenses), stationed at a distance from the border and created mainly by cavalry, was to help in particularly vulnerable places. Also new was the introduction of a total separation of civil and military power.

The tetrarchy system did not survive its creator, but Diocletian’s reforms strengthened the Roman state for almost two hundred years and allowed to defend effectively the borders to the beginning of the fifth century CE. His reign was an attempt to save the unity of the Roman Empire.

However, after the death of the emperor, the division tendencies intensified. In 395 CE, the emperor Thedosius the Great (379-395 CE) divided the empire into two parts: eastern and western. This division proved to be permanent and to some extent contributed to the fall in 476 CE of the western part.

  • Krawczuk Aleksander, Poczet cesarzy rzymskich, Warszawa 2004
  • Ziółkowski Adam, Historia Rzymu, Poznań 2008

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