Diocletian is not, properly speaking, a soldier, although he comes from the army's ranks, having lived most of his life in military camps (these may have been either in Gaul, as reported in the Historia Augusta, or in Moesia), he The empire is too great for one man to administer; nearly every week, either in Africa, or somewhere on the frontier that extends from Britain to the Persian Gulf, along the Rhine, the Danube, the Pontus Euxinus (Black Sea), and the Euphrates, he has been forced to suppress a revolt or stop an invasion.

Diocletian and his lieutenants have in the past six months calmed the stirrings of revolt among Roman troops stationed on the frontiers.

He is in Nicomedia in the beginning of 286, and from this point forward, he dedicates himself to restoring civil order to the empire by removing the army from politics.

Being more attracted to administration, Diocletian requires a man who is both a soldier and a faithful companion to take responsibility for military defense.

He now makes an unexpected decision-to share the throne with a colleague of his choice.

He chooses Maximian, an Illyrian, the son of a peasant from the area around Sirmium, whom he had made Caesar in 285, and now makes him Augustus.

A little later, though still keeping Rome as the official capital, he chooses two other residences.

Diocletian establishes himself at Nicomedia, in western Anatolia and close to the Persian frontier, in order to keep watch on the East.

Constantine, son of the emperor Constantius Chlorus, had been seen as a youth by his future panegyrist, Eusebius, bishop of Caesarea, passing with Diocletian through Palestine on the way to a war in Egypt.

Constantine’s experience as a member of the imperial court—a Latin-speaking institution—in the Eastern provinces will leave a lasting imprint on him.

Educated to less than the highest literary standards of the day, he will always be more at home in Latin than in Greek.

Christianity he encounters in court circles as well as in the cities of the East; and from 303, during the great persecution of the Christians that began at the court of Diocletian at Nicomedia and is enforced with particular intensity in the eastern parts of the empire, Christianity has become a major issue of public policy.

It is even possible that members of Constantine's family are Christians.

Licinius adds the entire eastern half of the empire to his dominion.

In the same year, he marries Constantine's half sister Constantia.

During the campaign against Maximinus, Licinius has made his army use a monotheistic form of prayer closely resembling that will later be imposed by Constantine.

On June 5, 313, he issues an edict granting toleration to the Christians and restoring church property.

Hence, his contemporaries, Lactantius and Eusebius, hail him as a convert.

Around 305, after Diocletian began persecuting Christians, Lactantius had resigned his post as teacher of rhetoric at Nicomedia and begun a scholarly work on a systematic Latin summary of Christian teaching, Divinae institutiones (“Divine Institutions”), which he completes in about 313.

He now becomes tutor to Constantine’s son Crispus.

Licinius has built up his army and accumulated a huge reserve of treasure during the years of uneasy peace between the Roman Empire’s two Augusti.

Having eventually become alienated from the Christians, he initiates a mild form of persecution in about 320, prompting contemporaries to paint the growing conflict between Constantine and his eastern counterpart as a battle between the forces of paganism and Christianity.

Constantine, after his victory over Licinius in 324, writes that he has come from the farthest shores of Britain as God's chosen instrument for the suppression of impiety, and in a letter to the Persian king Shapur II he proclaims that, aided by the divine power of God, he has come to bring peace and prosperity to all lands.

The Arian heresy, with its intricate explorations of the precise nature of the Trinity that are couched in difficult Greek, is as remote from Constantine's educational background as it is from his impatient, urgent temperament.

In a letter to the chief protagonist, Arius of Alexandria, Constantine states his opinion that the dispute had been fostered only by excessive leisure and academic contention, that the point at issue is trivial and can be resolved without difficulty.

…the emperor is forced to take to his bed near Nicomedia.

Here, Constantine receives baptism, putting off the imperial purple for the white robes of a neophyte; and he dies on May 22, 337.

He is buried at Constantinople in his Church of the Apostles, whose memorials, six on each side, flank his tomb.

This is less an expression of religious megalomania, however, than of Constantine's literal conviction that he was the successor of the evangelists, having devoted his life and office to the spreading of Christianity.

One of his final decrees had been the abolition of crucifixion within the Roman Empire.