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Constantius I Chlorus

(31 March 250 - 25 July 306 CE)

This post is also available in: Polish (polski)

Constantius I Chlorus

Gaius Flavius Constantius

Ruled as

Imperator Caesar Gaius Flavius Valerius Constantius Augustus


1 May 305 – 25 July 306 n.e.


31 March 250 CE


25 July 306 CE

Coin of Constantius I Chlorus

Almost everyone knows the achievements of Constantine the Great. However, not everyone knows that Constantine the Great owes the most to his father – a good and efficient emperor who rose to the top of his career almost from scratch. Who was the father of the great emperor? What has he done? Under what circumstances did he receive the purple? How did he end up in a relationship with a saint? What kind of man was Constantius Chlorus?

Beginnings of career

Constantius was born in 250, during the reign of Emperor Decius. He was born into a poor family living on the Danube in Illyria. The 3rd century in the Roman Empire was a period of turbulent wars, usurpations and barbarian invasions of border areas. Constantius, like probably many young people at that time, chose the obvious and most promising career in the army. He could not count on connections among the higher classes and possible protection, and yet he was promoted very high, most likely only thanks to his outstanding abilities. Constantius became a member of the imperial bodyguard, a military tribune, and then governor of the province of Dalmatia. After 280, while stationed in Naissus (today’s Niš in Serbia), he met Helena, the daughter of an innkeeper from Bithynia, with whom he became involved. This is a very important figure because he had a huge impact on the course of history in later years.

It is worth mentioning that later, when Constantius took the throne, his family was descended from Emperor Claudius II the Gothic, who reigned in the years 268-270. However, this was only a prestige custom that was widely practiced in those days.

The road to power

The military career of Constantius dates back to the times of emperors Aurelian and Probus. From 284, Diocletian took power in the Empire and began radical reforms in almost every field. Knowing that it was impossible to control the entire Empire alone, he introduced the principle of dividing the empire. From 285, Augustus Maximian was to rule in the West, and Diocletian himself in the East. Over time, this division turned into a tetrarchy. Each of the two Augustus was to appoint his successor and co-ruler – Caesar. Importantly, it could not be a descendant of any of them. In this way, there were to be a total of four rulers in the Empire. After twenty years, the Augustians were to “retire”, and their place was taken by the Caesars, who appointed their deputies for the next twenty years, etc. This was what opened up an opportunity for Constantius.

Group of Tetrarchs, sculpture from the beginning of the 4th century

Constantius found himself in the West with Maximian, who quickly noticed his abilities. He decided to make him his successor in the future. For this purpose, in 289 Constantius became Maximian’s son-in-law, and already in 293 he became Caesar at his side.

Caesar and Augustus

Constantius, as Caesar, became Maximian’s faithful assistant. He received from his father-in-law the task of ruling Gaul and Britain (see: Map of the tetrarchy in the years 293-305). However, it was not an easy task.

From 286/287, Britain was ruled by the usurper Carausius, a former high-ranking officer and commander of Maximian’s fleet. Constantius had to defeat him. The young Caesar’s quick actions caused a rebellion in Britain and the murder of Carausius in 293. Allektus became the new usurper. In 296, Constantius invaded the British Isles. A quick campaign preceded by a landing allowed Allektus to be overthrown, and Constantius entered Londinum and gained full control over the province.

Constantius I Chlorus (whose nickname means “pale”, probably due to his complexion) was also very active in Gaul. He defeated the Franks on the Rhine and improved the economy of Gaul, which was ruined by barbarian invasions and colonial uprisings.

[ramka_ze_zdjeciemimg=”127873″ alt=”Map of the tetrarchy in 293-305 CE” imgw=”600″ float=”center”]Map of the tetrarchy in 293-305 CE[/ramka_ze_zdjeciem]

From 303, Diocletian introduced strict edicts against Christians throughout the Empire. Thus began the greatest persecution in Roman history. However, Constantius pursued a policy of tolerance in the areas under his control, and Diocletian’s edicts were not implemented by him. This may be due to the fact that Christianity was not yet that widespread in the West. Christian historians such as Lactantius emphasize that Constantius limited himself only to the destruction of churches.

Caesar himself was most likely a worshiper of a solar deity called Sol Invictus (The Invincible Sun). However, it is suspected that there may have been sympathy for the Christian religion in his family.

In 305, as previously agreed, Diocletian and Maximian gave up power after twenty years. Constantius I Chlorus became Augustus of the West.


After 280, Constantius became involved with a poor girl named Helena from Bithynia in Asia Minor. She had a son, Konstantyn, who, like his father, chose a military career. It is not entirely known what the status of Helena’s relationship with Constantius was. Perhaps it was a marriage, or perhaps just a permanent informal relationship.

In 289, Constantius was forced to put Helen aside in order to marry Theodora, Maximian’s daughter. In this way, he became Augustus’ son-in-law, so that in 293 he could become co-ruler and his successor. With Theodora he had three sons and three daughters. The daughter Constance later became the wife of Emperor Licinius, and the son Julius Constantius became the father of the future emperor Julian the Apostate.

The decline of the reign and death

At the end of 305, the situation in the Empire was as follows: in the West, Augustus was Constantius, who was also the oldest ruler. The departing Maximian appointed his assistant and successor – Flavius ​​Severus. In the East, Diocletian was succeeded by Galerius Augustus, and his successor by Maximus Daia, his nephew. Moreover, Flavius ​​Severus was a good friend of Galerius. Therefore, Augustus Galerius had the greatest influence in the Empire, even though Constantius was the oldest.

The historian Eutropius described Constantius this way:

He was an outstanding man, full of great civic virtues. He wanted the inhabitants of the provinces and private people in general to become rich, but he did not care much about benefits for the state treasury. [..] He ran a manor house so modest that on holidays, when he hosted parties for larger numbers of friends, the tables were set with silver, which was borrowed from house to house. The people of Gaul not only loved him, but worshiped him, for thanks to his rule they escaped both the suspicious horrors of Diocletian and the explosive recklessness of Maximian1.

In the spring of 306, the seriously ill Constantius wanted to see his son Constantine, who was staying at the court of Galerius (most likely, under the guise of study and career, he was actually an unofficial hostage). Constantine fled from the court in Nicomedia immediately, for he rightly feared an ambush from the suspicious Galerius. However, he did not have time to kill him, and Constantine arrived in Gaul, escaping from the pursuit. Seriously ill, Constantius was preparing a military expedition against the Picts invading Britain from the north. He led it, and after its completion he died in the presence of his firstborn son on July 25, 306, in a military camp in Eburakum (today’s York in England). The universally liked emperor was the first of the tetrarchs to be included among the gods.


Immediately after Constantius’ death, his legions proclaimed his son Constantine emperor. It is not known whether it was his inspiration or he was forced to do it. In any case, the ambitious Constantine adopted the purple, which was the first departure from previously accepted rules. This initiated a series of conflicts for power and the fall of the tetrarchy, when in 312 Constantine and Licinius remained the only rulers. Over time, Constantine gained full power in the Empire, and his reign became a breakthrough. He was very much like his father in his character and decisions. His mother Helena, the first most important woman in Constantius’s life, as empress largely inspired her son’s policy. Thanks to her efforts, the relics of Christ’s cross were found. Today she is considered a saint.

Constantine the Great and his mother Saint Helena Helena

Constantine fully deserved his nickname “The Great”. His reign changed the course of the history of the Roman Empire and Christianity, and therefore the world. But would this “Great Emperor” be great if not for his father – the good and universally liked Emperor Constantius I Chlorus?

Author: Wojciech Buzała (translated from Polish: Jakub Jasiński)
  1. Own transalation from Polish.
  • Eutropiusz, Brewiarium od założenia Miasta
  • Aleksander Krawczuk, Poczet Cesarzy Rzymskich, Warszawa 2006
  • Wiesław Kaczanowicz, Uzurpacja Karauzjusza i Allektusa w Brytanii i Galii u schyłku III w. n.e., Katowice 1985

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