Constantine was educated in Latin and Greek at the court of Diocletian, the Eastern Roman emperor.
In 293 Constantin's father became the son-in-law and caesar (successor-designate) of Emperor Maximian, who was co-ruler of the Roman Empire with Emperor Diocletian. In 305 Diocletian and Maximian abdicated, and Chlorus became co-ruler, having superintendence of the West, while Galerius, Diocletian's son-in-law, superintended the East. The new emperors chose caesars (Maximinus Daia and Falvius Valerius Severus) who were not their relatives.
Galerius kept Constantine, who had distinguished himself as a soldier, at his own court, apparently fearing that he might develop imperial ambitions if left with his father. In 306, however, Constantine managed to escape to the West and joined Chlorus in campaigns in northern Britain. Chlorus died at York in July 306, and his troops immediately proclaimed Constantine his successor. Galerius acknowledged Constantine as a caesar, and he raised Severus to the role of emperor (augustus) in the West.
Constantine's dynastic elevation set a bad example. Thereupon Maxentius, old Maximian's son, proclaimed himself augustus in Italy, killed Severus, and obtained Africa as well. He quarreled with his father, however, and Maximian fled to Constantine, gave him his daughter Fausta in marriage, and supported Constantine's pretensions as an augustus.
From 307 to 311 five men claimed the rank of augustus: Galerius, Maxentius, Maximinus Daia, Licinius (Severus's successor), and Constantine. But in 310 Maximian entered into a conspiracy against Constantine, and upon its discovery Constantine had his father-in-law strangled. This event was immediately followed by war with Maxentius, who was defeated and drowned at the Battle of the Milvian Bridge in 312. In the East, Galerius had died in 311; and in 313 Maximinus Daia died after being defeated by Licinius.
By 313 Constantine and Licinius were established as co-rulers of the Roman world. Their relationship was cemented in that year by the marriage of Licinius to Constantine's half-sister Constantia; but jealousy and ambition generated friction and suspicion between the emperors, and in 323 war broke out after Constantine had violated Licinius's territory. Licinius was defeated and deposed, but his life was spared at the intercession of Constantia. The following year, however, Constantine found it expedient to execute him.
After his defeat of Licinius, Constantine was inspired to found a new imperial residence on the Bosporus at the site of ancient Byzantium. Constantinople had a magnificent harbor, the site was easily defensible, and strategically it was more or less equidistant from the dangerous Danubian and Persian frontiers. Constantine ransacked the pagan world for treasures with which to adorn his city, and he spirited a population to it by offering estates in Asia Minor to nobles who would build palaces there and, in an analogy to the Roman dole, by inaugurating rations of food for humbler immigrants.
The founding of Constantinople had far-reaching consequences. Rome was reduced in importance as the capital of the Roman Empire, and the western part of the empire continued to achieve increasing autonomy. The Roman Senate, hitherto a powerful instrument of government, became little more than Rome's city council. The establishment of Constantinople as a de facto second capital hastened the bipartition of the Roman Empire.
Constantine did not neglect the security of the frontiers. Constantine won major victories over the Franks and Alamanni in 306–308, the Franks again in 313–314, the Goths in 332 and the Sarmatians in 334. By 336, Constantine had reoccupied most of the long-lost province of Dacia, which Aurelian had been forced to abandon in 271.
Constantine's conversion to Christianity has generated much discussion. In later years he told the historian Eusebius that before his encounter with Maxentius he had seen a cross of light superimposed on the sun with the inscription above it: in hoc signo vinces (in this sign you shall conquer). Since the cross was the Christian symbol, he had his troops inscribe the monogram of Christ on their shields before the Battle of the Milvian Bridge, and his subsequent success in battle convinced him that he had the protection of the Christian god.
Theretofore Constantine had probably been a worshiper of the Unconquered Sun, and in the beginning he appears to have thought that Christ and the Sun were identical. Constantine's coinage for some time continued to celebrate the Sun, and as late as 321 his order for the observation of Sunday gave as a reason that the day was solemnized "by the veneration of the Sun." But Constantine's early involvement in the theological disputes of the Christians soon disabused him of any syncretistic notions.
Early in his reign a group of puritanical followers of Donatus in Africa charged that the orthodox Catholics were too lenient toward penitent apostates, and their quarrels reached the Emperor. He tried for years to reconcile or suppress the dissidents but ultimately gave up his efforts in despair.
More serious were the quarrels concerning the nature of the godhead. A heresy called Arianism, which maintained that Christ was not co-eternal with the Father, scandalized many churchmen. Roman emperors, as heads of the state religion, had always been responsible for keeping the gods at peace with men (pax deorum). Now it appeared that the Emperor must secure a pax dej, lest God be offended at His people's view of His nature.
Therefore, in May 325 Constantine convened a council of bishops at Nicaea in Bithynia. This convocation created the Nicene Creed, which established the orthodox view that Christ was of the same substance (homoousios) as the Father but was a separate individual. The decisions of the council by no means pleased everyone, and Constantine was engaged in attempts to heal theological schisms right up to his death. Indeed, he was baptized on his deathbed by an Arian.
Constantine's personal religious views have been a puzzle to historians. He continued throughout his life to hold the post of pontifex maximus of the old religion. And he allowed the continued celebration of ancient cults and even the erection of temples in honor of his family, though he specified that worship in them must not include "contagious superstition." The Edict of Milan (313) by Constantine and Licinius conferred toleration on all religious sects but did not establish a state church.
But as time went on, Constantine showed increasing favor to the Christians. He built and endowed magnificent churches at Constantinople and Rome and in the Holy Land, Asia Minor, and Africa. He established allowances of grain for the support of the clergy and the poor. He legalized bequests to churches and gave bishops the right to free slaves as well as the right to judge quarrels between Christians without the right of appeal to civil courts. Many of his favorite officials were Christians, and the education of his sons was put in Christian hands.
While the celebration of pagan rites continued, a few temples were ordered closed, and others were destroyed by Christian mobs without subsequent imperial punishment. Indeed, Constantine himself had some temples plundered, and only the wooden frames of chryselephantine cult statues were left for the worshipers. Here the decisive factor seems to have been the need for the gold and silver sheathing of the statues to help finance the Emperor's elaborate building program.
Constantine continued and elaborated the army reforms begun by Diocletian. He created a large central and mobile army, which could be quickly dispatched to any troubled frontier. Civil and military authority in the provinces was carefully divided; and the new army appears to have been under the command of a master of infantry and a master of cavalry. The number of barbarians in the army increased, and Constantine is said to have favored Germans.
Constantine also followed Diocletian in the elaboration of court ritual. He instituted the order of imperial companions (comites) and classified them by grades, depending on the offices they held. Grandiloquent titles abounded, and recipients were favored by reduced tax burdens and fewer civic duties. He also gave the ancient title of patrician to close friends and high officials.
The cost of Constantinople, increased pay for the army and bureaucracy, and lavish grants to the Church and to favorites combined to create multiple financial problems. To meet these Constantine had the accumulated wealth of the parsimonious Licinius and the confiscated treasures of pagan temples. These were supplemented by new taxes on merchants and craftsmen, surtaxes on the land, and a gradual increase of customs dues and other local levies.
Constantine's most constructive financial contribution was the creation of the gold solidus, struck at 72 to the pound, which maintained its purity until the 11th century. But the economy remained weak and the burdens of government heavy. To ensure the performance of essential services, Constantine became more and more authoritarian. As early as 313 he had ordered local senators (curiales) bound to their positions because they were liable for the collection and guarantee of taxes. By the end of his reign their duties had become hereditary.
Similarly, shipmasters were compelled to remain on their jobs, for the transport of food to cities was not financially attractive. And in 332 tenant farmers were threatened with a reduction to slavery if they left their districts, thus swiftly moving agricultural workers to serfdom. These measures of Constantine rapidly moved the Roman world from a regime of contract to a regime of status, wherein citizens were tied from birth to their places of origin and their professions.
"Thinking is the great enemy of perfection. The habit of profound reflection, I am compelled to say, is the most pernicious of all the habits formed by civilized man."
"With Free minds all are to worship their Gods."
Quotes from others about the person
`Abdu'l-Bahá: "The first person to establish public clinics throughout the Roman Empire where the poor, the injured and the helpless received medical care, was the Emperor Constantine. This great king was the first Roman ruler to champion the Cause of Christ. He spared no efforts, dedicating his life to the promotion of the principles of the Gospel, and he solidly established the Roman government, which in reality had been nothing but a system of unrelieved oppression, on moderation and justice. His blessed name shines out across the dawn of history like the morning star, and his rank and fame among the world's noblest and most highly civilized is still on the tongues of Christians of all denominations."
John Dalberg-Acton, 1st Baron Acton: "Constantine declared his own will equivalent to a canon of the Church. According to Justinian, the Roman people had formally transferred to the emperors the entire plenitude of its authority, and, therefore, the emperor’s pleasure, expressed by edict or by letter, had force of law. Even in the fervent age of its conversion the empire employed its refined civilization, the accumulated wisdom of ancient sages, the reasonableness and subtlety of Roman law, and the entire inheritance of the Jewish, the pagan, and the Christian world, to make the Church serve as a gilded crutch of absolutism."
Akiva Goldsman: "Constantine may have been a lifelong pagan but he was also a pragmatist and in 325 Anno Domini he decided to unify Rome under a single religion, Christianity.… And to strengthen this new Christian tradition, Constantine held a famous ecumenical gathering known as the Council of Nicaea, and at this council the many sects of Christianity debated and voted on well, everything from the acceptance and rejection of specific gospels to the date for Easter to the ministry of sacrament, and of course, the immortality of Jesus."
John Howard Yoder: "For the early Church, "church" and "world" were visibly distinct yet affirmed in faith to have one and the same lord. This pair of affirmations is what the so-called Constantinian transformation changes (I here use the name of Constantine merely as a label for this transformation, which began before AD200 and took over 200 years; the use of his name does not mean an evaluation of his person or work). The most pertinent fact about the new state of things after Constantine and Augustine is not that Christinas were no longer persecuted and began to be privileged, nor that emperors built churches and presided over ecumenical deliberations about the Trinity; what matters is that the two visible realities, church and world, were fused. There is no longer anything to call "world"; state, economy, art, rhetoric, superstition, and war have all been baptized."
Constantine's relations with his family were not marked by Christian love or charity. He was a calculating and suspicious man, perhaps as a result of his struggle to survive as a youth among the intrigues at the court of Galerius. In any case, during his career he contrived the death of his father-in-law (Maximian) and of two brothers-in-law (Maxentius and Licinius); in 326 he suddenly, and for obscure reasons, executed his eldest and much admired son (by his first marriage to Minervina), the Caesar Crispus, and apparently at the same time he killed his nephew Licinianus, who was only 11 years old.
It is widely believed that Crispus's fall may have been due to the jealous ambition of his stepmother, Empress Fausta, in behalf of her own three sons. If so, there was an early revulsion of feeling, for she was drowned in her bath in less than a year. By her Constantine had three sons, Constantine II, Constantius, and Constans. They, along with Dalmatius and Hannibalian, sons of Constantine's brother Dalmatius, were made caesars and given the administration of various parts of the empire as though it were Constantine's personal estate.
Except for these three sons and two infant nephews (Gallus and Julian) all of Constantine's close relatives, including his half brothers Dalmatius and Julius Constantius, were lynched by the army at Constantine's death, leaving Fausta's brood to fight over the inheritance.