Flavius Valerius Constantius^[1] (March 31 c. 250 – July 25, 306), also Constantius I, was an emperor of the Western Roman Empire (305–306). He was commonly called Chlorus (the Pale)^[2] an epithet given to him by Byzantine historians. He was the father of Constantine the Great and initiator of the Constantinian dynasty.

 History

The Historia Augusta says Constantius was the son of Eutropius, a noble from northern Dardania in modern Serbia, and Claudia, a niece of the emperors Claudius II and Quintillus.^[3] Historians, however, suspect this maternal connection to be a genealogical fabrication created by his son Constantine I, thus connecting his family to two rather highly regarded predecessors. His father, however, might have been the brother of Eutropia, wife of Maximian.

Under the emperor Carus, he was governor of Dalmatia, and Carus is said to have considered adopting him as his heir in place of his dissolute son, Carinus.^[4]

In 293 the emperor Diocletian created the Tetrarchy, dividing the Roman Empire into Western and Eastern portions. Each would be ruled by an Augustus, supported by a Caesar. Diocletian became Augustus of the Eastern empire, with Galerius as his Caesar. Constantius was appointed Caesar to the Western Augustus, Maximian, and married Theodora, Maximian's stepdaughter. They had six children. Constantius divorced his first wife (or concubine), Helena, by whom he already had a son, Constantine. Helena was probably from Nicomedia in Asia Minor.^[5] He was given command of Gaul, Britain and possibly Hispania.

In 293, Constantius defeated the forces of Carausius, who had declared himself emperor in Britain and northern Gaul in 286, near Bononia. Carausius was killed by his rationalis Allectus, who took command of Britain until 296, when Constantius sent Asclepiodotus, a prefect of the Praetorian Guard, to invade the island. Allectus was defeated and killed, and Roman rule in Britain restored.^[6]

Also in 296, Constantius fought a battle against the Alamanni at the city of Lingonae (Langres) in Gaul. He was shut up in the city, but was relieved by his army after six hours, and defeated the enemy.^[7] He defeated them again at Vindonissa (Windisch, Switzerland),^[8] thereby strengthening the defenses of the Rhine frontier.

Diocletian and Maximian stepped down as co-emperors in 305, possibly due to Diocletian's poor health, and the Caesars, Constantius and Galerius, became co-emperors. Constantius ruled the western empire, Galerius the eastern. Severus and Maximinus Daia were appointed Caesars. Constantine, who had hoped to be a Caesar, joined his father's campaigns in Gaul and Britain.^[9] Constantius died in Britain, at York, in 306, and Constantine was declared emperor by the army.^[10]

 Legend

 Christian legends

As the father of Constantine, a number of Christian legends have grown up around Constantius. Eusebius's Life of Constantine claims that Constantius was himself a Christian, although he pretended to be a pagan, and while Caesar under Diocletian, took no part in the emperor's persecutions.^[11] His first wife, Helena, is the subject of many legends, including the finding of the True Cross.

 British legends

Constantius's activities in Britain were remembered in medieval British legend. In Geoffrey of Monmouth's History of the Kings of Britain (1136), he is sent to Britain by the Senate after Asclepiodotus, here a British king, is overthrown by Coel of Colchester. Coel submits to Constantius and agrees to pay tribute to Rome, but dies only eight days later. Constantius marries Coel's daughter Helena and becomes king of Britain. He and Helena have a son, Constantine, who succeeds to the throne of Britain when his father dies at York eleven years later.^[12] The identification of Helena as British had previously been made by Henry of Huntingdon,^[13] but has no historical validity: Constantius had divorced Helena before he went to Britain.