Constantius Chlorus
"Constantinian propaganda bedevils assessment of Constantius, yet he appears to have been an able general and a generous ruler." That verdict comes from the Oxford Classical Dictionary. It frames the central difficulty with Constantius Chlorus, a Roman emperor who ruled the western world at the turn of the fourth century. His son Constantine the Great, the first Christian emperor of Rome, had compelling reasons to shape how later ages remembered his father. Even the name Chlorus was not Constantius's own. Byzantine-era historians coined it long after his death, and he never heard it applied to himself. He rose from humble provincial origins to command nearly half the Roman Empire. The real Constantius, filtered through layers of imperial image-making, is a figure worth recovering. His birthday fell on the 31st of March, though the year of his birth was already uncertain to the ancients.
Moesia Superior, a Roman province on the south bank of the Middle Danube, is where Constantius came from, probably born around 250. Ancient sources disagreed about who his parents were. The unreliable Historia Augusta named his father as Eutropius, a nobleman from that province. His mother, the same text claimed, was Claudia, a niece of the emperor Claudius Gothicus. Modern historians are skeptical of that lineage. Constantine probably fabricated that aristocratic genealogy to distance his father from any association with the emperor Maximian. Constantius was more likely Thracian or Illyrian, from a family that left no certain name in the record.
As a member of the Protectores Augusti Nostri, the imperial guard corps, Constantius served under Aurelian and fought against the Palmyrene Empire in the east. By the reign of Carus he had risen to praeses, governor of the province of Dalmatia. He probably backed Diocletian just before the Battle of the Margus in July 285, when Diocletian consolidated power in the west. By 288, he was serving as Maximian's praetorian prefect. Throughout 287 and into 288, under Maximian's command, he fought the Alamanni across the Rhine and Danube borders.
Around 289, political pressures required Constantius to divorce Helena. Helena, the mother of Constantine, was probably from Nicomedia in Asia Minor. He married instead Theodora, Maximian's daughter, tying himself by blood to the ruling western augustus. On the 1st of March 293, at Mediolanum, Maximian formally appointed Constantius as caesar. Constantius adopted Diocletian's family name, Valerius, and also took the name Herculius from Maximian's household. His capital was placed at Augusta Treverorum, the city now called Trier. On official documents, his name always came before that of Galerius, the eastern caesar. Diocletian had elevated Galerius, possibly on the 21st of May 293 at Philippopolis. Constantius's first assignment as caesar was the usurper Carausius. Carausius had declared himself emperor in Britannia and northern Gaul in 286 and had held both territories ever since.
In late 293, Constantius captured the key port of Bononia, now called Boulogne-sur-Mer, and defeated Carausius's forces in Gaul. Carausius did not survive to face what came next. His own finance officer, Allectus, assassinated him and took command of the British provinces, holding them until 296. Constantius spent the following years clearing northern Gaul of the Frankish allies who had backed Allectus. He also won victories against the Alamanni at the mouth of the Rhine in 295.
When Constantius judged the moment right, he assembled two invasion fleets to cross the English Channel. The first was placed under Julius Asclepiodotus, his long-serving praetorian prefect, who sailed from the mouth of the Seine. Constantius commanded the second fleet himself, launching from Bononia. Asclepiodotus landed near the Isle of Wight, engaged Allectus's army, and killed the usurper. Constantius, meanwhile, sailed into Londinium in time to prevent an attack by Frankish mercenaries left without a paymaster. He massacred them all.
Constantius remained in Britannia for several months. He replaced most of Allectus's officers and oversaw a reorganization of the provinces. Britannia Superior was divided into Maxima Caesariensis and Britannia Prima, while Flavia Caesariensis and Britannia Secunda were carved from Britannia Inferior. He also restored Hadrian's Wall and its forts along the northern boundary. Back across the Channel, in 298, Constantius fought the Battle of Lingones against the Alamanni, a fight he came close to losing.
At Lingones, the city now called Langres, the Alamanni trapped Constantius inside the walls in 298. His army had not yet arrived. Within six hours, his forces reached the city and broke the siege. Constantius then defeated the Alamanni again at Vindonissa, deepening the Rhine defenses.
In 300, Constantius moved against the Franks on the Rhine frontier. Rather than simply pushing them back, he settled Frankish communities in the depopulated parts of Gaul, repopulating land the wars had emptied. The Rhine frontier continued to demand his attention for the next three years. Between these campaigns, administrative duties required at least one journey to Italy.
The edicts Diocletian issued in 303 ordered the demolition of churches across the empire and the active suppression of Christians. Three of the four Tetrarchs moved swiftly to comply. Galerius, the eastern caesar, was especially eager. He had observed that Constantius was sympathetic to Christians, and he saw rigorous enforcement as a means of gaining ground with the aging Diocletian. Of the four co-emperors, Constantius made the least effort.
Constantius limited himself to knocking down a handful of churches in the western provinces. Ancient sources cannot even agree on that much. Eusebius, the early church historian, denied that Constantius destroyed any Christian buildings at all. Lactantius, another Christian writer of the period, recorded that he did demolish some. What is consistent is what Constantius did not do. He did not pursue Christians, imprison them, or demand that they sacrifice to Roman gods. The name of his daughter Anastasia may indicate a sympathy with Christian or Jewish culture. Between 303 and 305, Galerius worked to ensure that Constantius's son Constantine would be excluded from the succession when power changed hands.
On the 1st of May 305, at Mediolanum, Maximian removed his purple cloak and handed it to Severus, Galerius's nominee as the new caesar. At the same moment, at Nicomedia in the east, Diocletian performed the same ceremony. Constantius became the senior augustus in the west. Constantine had been passed over for a junior post and fled Galerius's court after Constantius, claiming illness, asked for his son back. Constantine reached his father at the Gallic coast just as Constantius was preparing a campaign in Britain.
In 305, Constantius crossed into Britain and marched north, launching an expedition against the Picts beyond the Antonine Wall. The campaign succeeded. By the 7th of January 306, he had earned the title Britannicus Maximus for the second time. He withdrew to Eboracum for the winter, planning to resume operations in the spring. He never did. Constantius died at Eboracum on the 25th of July 306. As he lay dying, he named Constantine to the army as his successor, and the legions immediately acclaimed Constantine as emperor.
The proclamation at York destabilized the Tetrarchy. Civil wars followed, ending only in 324 when Constantine united the entire Roman Empire under his rule. The Constantinian dynasty that began with that deathbed recommendation governed Rome until the death of Constantius's grandson Julian in 363. Constantius himself became the subject of legend in both Christian and British tradition. Eusebius, in his Life of Constantine, claimed that Constantius had secretly been a Christian all along. Geoffrey of Monmouth's 1136 History of the Kings of Britain wove Constantius into a fictional narrative of British kingship with no historical basis. The History of the Britons, traditionally ascribed to Nennius, reported a tomb of Constantius the Emperor still visible in the 9th century. It stood at the Roman fort of Segontium, near present-day Caernarfon in North Wales. The scholar David Nash Ford later concluded the monument commemorated not Constantius at all, but a different ruler also named Constantine.
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Common questions
Who was Constantius Chlorus and why does he matter to Roman history?
Constantius Chlorus was a Roman emperor who served as caesar from 293 and became senior augustus of the western empire in May 305, ruling until his death on the 25th of July 306. He was the father of Constantine the Great and the founder of the Constantinian dynasty, which governed the Roman Empire until the death of his grandson Julian in 363.
When did historians first apply the name Chlorus to Constantius, and was it used in his lifetime?
The name Chlorus was a coinage of Byzantine-era historians, popularized long after Constantius's death, and was never used during the emperor's lifetime. His formal name was Marcus Flavius Valerius Constantius.
What did Constantius Chlorus accomplish in Britain?
Constantius Chlorus reconquered Britain from the usurper Allectus in 296 by launching two invasion fleets across the English Channel. His praetorian prefect Julius Asclepiodotus landed near the Isle of Wight and defeated Allectus, while Constantius occupied Londinium and killed Frankish mercenaries who were threatening the city. He also reorganized the British provinces and restored Hadrian's Wall.
What was Constantius Chlorus's role in the Tetrarchy?
Constantius Chlorus was formally appointed caesar by Maximian at Mediolanum on the 1st of March 293, making him one of the four original members of Diocletian's Tetrarchy. He ranked as the more senior of the two caesares and on official documents always took precedence over Galerius. In May 305, when Diocletian and Maximian abdicated, he became senior augustus of the western provinces.
How did Constantius Chlorus treat Christians during the Diocletianic Persecution?
Of the four Tetrarchs, Constantius Chlorus made the least effort to enforce the Diocletianic Persecution, which began in 303. He limited himself to demolishing a handful of churches and did not pursue, imprison, or require sacrifices from Christians. Ancient sources disagree even on that: Eusebius denied he destroyed any Christian buildings, while Lactantius recorded that he did.
Where and when did Constantius Chlorus die?
Constantius Chlorus died on the 25th of July 306 at the Roman fortress of Eboracum, the city now called York. He had just completed a campaign against the Picts in northern Britain. As he lay dying, he named his son Constantine as his successor, and the legions at York immediately acclaimed Constantine as emperor.
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24 references cited across the entry
- 2BookThe New Empire of Diocletian and ConstantineTimothy D. Barnes — Harvard University Press — 1982
- 3Oxford Dictionary of ByzantiumTimothy E. Gregory — Oxford University Press — 1991
- 6JournalWhat's in a Name? A Survey of Roman Onomastic Practice from c. 700 B.C. to A.D. 700Benet Salway — 1994
- 7The Oxford Dictionary of Late AntiquitySarah Bond et al. — Oxford University Press — 2018
- 9BookOxford Classical DictionaryRaymond Davis — Oxford University Press — 22 December 2015
- 11BookJulian the ApostateShaun Tougher — Edinburgh University Press — 2007
- 12Murray (1999) p. 221Murray — 1999
- 16The Cambridge Illustrated History of the Roman WorldGreg Woolf — Cambridge University Press — 2003
- 17AllectusLeonhard Schmitz — Little, Brown and Company — 1867