Flavius Valerius Aurelius Constantinus (27 February ca. 272 – 22 May 337 AD), commonly known as Constantine I, (among Roman Catholics) and Constantine the Great, or Saint Constantine (among Eastern Orthodox and Byzantine Catholic Christians),proclaimed Augustus by his troops in 306, who ruled an ever-growing portion of the Roman Empire until his death. Best known for being the first Christian Roman Emperor, the Edict of Milan - issued by his co-emperor Licinius - helped to put an end to institutionalized persecution of Christians in the Empire.

The Byzantine liturgical calendar, observed by the Eastern Orthodox Church and Eastern Catholic Churches of Byzantine rite, lists both Constantine and his mother Helena as saints. Although he is not included in the Latin Church's list of saints, which does recognize several other Constantines as saints, he is revered under the title "The Great" for his contributions to Christianity.

In 324, Constantine announced his decision to transform Byzantium into Nova Roma and on May 11, 330, he officially proclaimed the city the new capital of the Roman Empire. The city was renamed Constantinople, The City of Constantine, after Constantine's death in 337. It would remain the capital of the Byzantine Empire for over a thousand years, a reign interrupted only briefly by its 1204 sacking and occupation in the Fourth Crusade, until it finally fell to the Ottoman Empire in 1453.

Constantine was born Flavius Valerius Constantinus in the Moesian military city of Naissus (Niš, Serbia) on the 27th of February of an uncertain year. Most historians assert 272 as his birth year, following a number of ancient sources, but another equally reliable contemporary source suggests a birthdate of 276, and modern historians have argued for dates as late as 288. In later years, he would often lie about his age for political purposes, further confusing the issue. In any case, Constantine was born in an age in which births were not regularly registered; it is likely that Constantine himself did not know exactly when he was born.

Constantine's father was Flavius Constantius, nicknamed "Chlorus", "the pale"; an Illyrian native of what would later become Dacia Ripensis. Constantine's mother was called Helena, a native of Bithynian Drepanum. Constantius was an officer in the Roman army at the time of Constantine's birth, serving as an imperial bodyguard to emperor Aurelian in Syria. The position proved favorable to Constantius' career: in 284/5, the newly incumbent emperor Diocletian, an Illyrian who had also served under Aurelian, appointed Constantius governor of Dalmatia. Helena was a woman of humble origin: one source claims her to be a mere concubine of Constantius, another calls her "extremely lowly", and another that she had been a mere stable maid when she met Constantius. More reliable sources generally agree that she was Constantius' legitimate spouse, and that Constantine was, indeed, a legitimate heir.

As emperor, Diocletian effected a systematic and comprehensive division of the Empire. Two emperors would rule the Empire, one in the East and one in the West, in a system called the Tetrarchy. Diocletian would rule the East from Nicomedia (İzmit), and an old Illyrian colleague, Maximian, would rule the West from Mediolanum (Milan). Each emperor would have his own court, his own military and administrative faculties, and each would rule with a separate praetorian prefect as chief lieutenant. In 288, Maximian appointed Constantius to serve as his praetorian prefect in Gaul. Constantius divorced Helena, and married Maximian's stepdaughter Flavia Maximiana Theodora ca. 289. Diocletian, dissatisfied with his first division, divided the Empire again in 293, appointing two Caesars—junior emperors—to rule over further subdivisions of East and West. Each Caesar would be subordinate to their respective Augustus—senior co-emperors Maximian and Diocletian—but each would act with supreme authority in their own assigned territories. Thus it was that, on March 1 293, Constantius was promoted to the office, and given the task of suppressing the usurper Carausius' rebellion in Britain and Gaul. Constantine, now a Caesar's son, thus became a potential candidate for future appointment as emperor. Constantine moved on to the court of Diocletian, where he lived as heir presumptive to his father's throne.

Young Constantine benefited greatly from his father's position. At the court of Diocletian, Constantine received a formidable education, gaining a skillful understanding of Latin literature, a capable proficiency in Greek, and an aptitude for philosophy. It is possible that he may have viewed the lectures of the Latin scholar Lactantius in Nicomedia. It is sometimes suggested, however, that Constantine was held as something of a hostage at Diocletian's court; Diocletian did not completely trust Constantius—none of the tetrarchs fully trusted their colleagues—and would have wished to have collateral to ensure good behavior. Constantine was nonetheless a prominent member of the court, and participated fully in the political life of the Empire. Constantine fought for Diocletian and Galerius in Asia, serving in a variety of tribunates. He campaigned against barbarians on the Danube in 296, fought in the Persian wars under Diocletian in Syria (297) and Galerius in Mesopotamia (298–99). He traveled to Babylon in Mesopotamia and Memphis in Egypt. Returning from his Egyptian voyage, he met the young Eusebius, his later biographer, in Caesarea Maritima in Palestine, and impressed him with his intelligence, strength, and natural grace.

In 298, Constantine traveled with Diocletian while on campaign against the Persians. He usually kept close to Diocletian, probably witnessing, on February 23 303, Diocletian's destruction of the newly-built Christian church at Nicomedia. The event inaugurated the "Great Persecution", a series of severe persecutions of Christians and Manichaeans that continued for eight years. Many Christians were imprisoned, tortured, and killed for acts of defiance against official religious policy, but most escaped punishment through silence. Constantine's silence in his role at Diocletian's court during the period engendered a continuing distrust among the church hierarchy for any participation on his part in church government. Constantine concealed the extent of his complicity. In a late letter to Eastern provincials, Constantine described himself as a child when the Great Persecution began, when in fact, he was nearer to thirty; his later biographers and panegyrists continued the trend, describing him as "the young man" or "the youthful emperor". No contemporary Christian challenged him on any aspect of his role in the persecutions. Nonetheless, Constantine asserted that he had criticized the policy when it was first introduced.

Diocletian had become increasingly sick over the winter of 304–5, following the contraction of a minor illness in the spring on the Danube. He had disappeared into his palace after November 304, and rumors of his imminent death circulated for months afterwards. When he at last appeared in public on March 1 305, he was emaciated and barely recognizable. His judgment and will power were seriously impaired, and he was left prey to the will of Galerius. In March, Galerius arrived in Nicomedia with plans to reconstitute the tetrarchy according to his will, and fill the imperial office with compliant candidates; through coercion and threats, he convinced Diocletian and Maximian to comply with his plan. On May 1 305, Diocletian, addressed an assembly of generals and his traditional companion troops, and informed them of his will to resign. Constantius was to succeed Maximian as Augustus of the West, Severus and Maximin were made Caesars. Although two legitimate sons of emperors were available (Constantine, as the son of Constantius, and Maxentius, as the son of Maximian), both were ignored in the transition of power. This perceived slight served to create instability within the Tetrarchy, and inspire jealousy in Constantine and Maxentius. These feelings were intensified in the case of Constantine by the fact that familial ties had helped to elevate Maximin, as Galerius' nephew, but had not helped Constantine himself at all. Galerius, recognizing Constantine's discontent, sent him off to war in hopes of killing him. Constantine's later propagandists record that he sent him to lead an advance unit in a cavalry charge through a swamp against the Sarmatians on the middle Danube. Against expectations, Constantine succeeded in leading his men to victory, and managed to grab a Sarmatian by the hair to present to Galerius upon his return to Nicomedia. Constantine continued to rise in rank, reaching the level of tribune of the first order by late 305.

Constantine recognized the implicit danger in remaining at Galerius' court, where he was held as a virtual hostage. His career depended on being rescued by his father in the west. Constantius, aware of the dangerous circumstances of his son, was quick to intervene. In the late spring or early summer of 305, Constantius requested leave for his son for help in combat operations against the Picts in Britain. Constantius' request was granted by Galerius during a long evening of drinking. Constantine's later propaganda describes how Constantine fled the court in the night, so as not to allow Galerius to change his mind in the morning. In the tale, Constantine gallops from post-house to post-house at high speed, hamstringing his horses along the way. He takes the route north of the Alps to avoid Severus, then in Italy. When Galerius awoke late the next morning, he attempted to revoke the order, only to find that Constantine had already fled. Regardless of the exact nature of his departure, Constantine joined his father in Gaul, at Bononia (Boulogne) by the summer of 305. From there they made their way to York. In northern Britain, Constantine was able to spend a year at Constantius's side, dispelling Pictish raiders beyond Hadrian's Wall in the summer and autumn. Constantius had become severely sick over the course of his tenure, and died on July 25 306 in Eboracum (York). Before dying, he declared his support for raising Constantine to the rank of full Augustus. The Alamannic king Chrocus, a man who had been defeated by and taken service under Constantius, proclaimed Constantine as Augustus. The troops loyal to Constantius' memory followed him. Word quickly spread of Constantine's acclamation; soon the whole of Gaul pledged him its allegiance.

Constantine's succession was contrary to Diocletian's original plans for his father's office, and therefore somewhat insecure. With Constantius' support and the backing of his armies, however, it mattered little. Nonetheless, since Constantine was now working directly beneath Galerius, he sent him an official notice of Constantius' death and his own acclamation. Along with the notice, he included a traditional portrait of himself robed in the outfit of Augustus of the West, wearing the imperial wreath. He requested recognition as heir to his father's throne, and passed off responsibility for his unlawful ascension on his army, claiming they had "forced it upon him". Galerius was displeased with the message, and almost set the portrait on fire along with the messenger who had brought it in his discontent. With difficulty, his advisers convinced him of the necessity of peace, and the difficulty of challenging such a popular man. Galerius was compelled to compromise. He sent Constantine a purple vestment—wishing to make it certain that Galerius remained the true source of power—and granted to him the title of Caesar. He gave the office of Augustus to Severus instead. Constantine accepted the decision, as it would remove any possible doubts regarding his legitimacy. He began appearing on imperial coinage as Flavius Valerius Constantius the Noble Caesar.

Constantine's share of the Empire consisted of Britain, Gaul, Germania, and Hispania. He therefore commanded one of the largest Roman armies, stationed along the important Rhine frontier. During his years in Gaul, from 306 to 316, Constantine continued his father's efforts to secure the Rhine frontier and rebuild the Gallic provinces. After his promotion to emperor, Constantine remained in Britain for a brief period of time, securing his control in the northwestern dioceses. While there, he completed the reconstruction of military bases begun under his father's rule, and ordered the repair of Roman roadways. Like all new emperors, he had busts made of his face to be set in major cities and military camps, and began printing currency with his profile. He soon returned to Augusta Treverorum (Trier) in Gaul, the tetrarchic capital. In the winter of 306–7, he made his way to Gaul to quell an uprising by the Franks, who had begun raiding Roman towns in Constantius' absence. Constantine drove them back across the Rhine, slaughtered many of their number, and captured two of their kings. In the victory celebrations that ensued in Trier, Constantine fed the kings and their warriors to beasts in the amphitheater. His actions cemented his reputation as a warrior, and ensured his popularity among his subjects.

After his victory, Constantine began a major expansion of Trier. He strengthened the circuit wall around the city with military towers and fortified gates, and erected the beginnings of a palace complex in the northeast of the city. Somewhat to the south of his palace, he ordered the construction of a large formal audience hall, and a massive imperial bathhouse. For the duration reign, Constantine would sponsor many building projects across his domain, especially in Augustodunum (Autun) and Arelate (Arles). Constantine also, in the account of Lactantius, followed his father in following a tolerant policy towards Christianity. Although not yet a Christian, he probably judged it a more sensible policy than open persecution. In his first years as one of the tetrarchs, Constantine's image transformed from that of the "bloodthirsty son of a renowned father" into that of an "august and fatherly emperor" who had simply outgrown the need for his father.

Meanwhile, Maxentius, the disinherited son of Maximian, began a rebellion against the rule of Severus in Italy. Taking advantage of Roman discontent at their taxation under Galerius', Maxentius persuaded a cohort of imperial guardsmen to declare him emperor, on October 28 306. Where Constantine was a qualified individual who filled an empty position in the tetrarchy, Galerius judged Maxentius to be an unworthy and disrespectful man seemed to wish to destabilize the whole tetrarchic system. What was more, Galerius hated him; he refused to recognize him, and sent Severus' armies against him. Maxentius brought his father Maximian out of an uncomfortable retirement to fight alongside him. Constantine decided to depart from Gaul and visit Britain in the spring and summer of 307, seeking to avoid the turmoil in Italy. Constantine wished to remain neutral in the conflict, sending no forces against either Maxentius or Galerius. Instead of participating in the civil war, Constantine used his troops against Germanic tribes along the Rhine. In 308, he raided the territory of the Bructeri, and made a bridge across the Rhine at Colonia Agrippinensium (Cologne). In 310, he marched to the northern Rhine and fought the Franks. When not campaigning, he toured his lands advertising his benevolence, and supporting the economy and the arts. His refusal to participate in the war increased his popularity among his people, and built him a stable power base in his provinces.

While Maxentius built up Rome's defenses, Maximian made his way to Gaul to confer with Constantine. He offered to espouse his younger daughter Fausta to him, and elevate him to Augustan rank. By way of recompense, Constantine would reaffirm the old family alliance between Maximian and Constantius, and offer support to Maxentius' cause in Italy. Constantine accepted, and married Fausta in Trier in late summer 307. Despite his marriage into the alliance, Constantine offered little to Maximian in return: political recognition and military neutrality. Maximian returned to Rome in the winter of 307–8, but soon fell out with his son. He challenged Maxentius' right to rule in the spring of 308 before an assembly of Roman soldiers. The soldiers sided with Maxentius. Having failed to depose his son, Maximian left Italy in disgrace and returned to the court of Constantine in Gaul in early 309, the only court that would accept him.

On November 11 308, Galerius called a general council at the military city of Carnuntum on the upper Danube to resolve the instability in the western provinces. In attendance were Diocletian, briefly returned from retirement, Galerius and Maximian. Maximian was forced to abdicate again and Constantine was again demoted to Caesar. Licinius, a loyal military companion to Galerius, was appointed Augustus of the west. The new system was not amenable to its constituents: Constantine refused to accept his second demotion, and continued to style himself as Augustus on his own coinage, even as other members of the tetrarchy referred to him as a Caesar on their own; Maximin Daia was frsutrated for having been turned over for a promotion while Licinius had been promoted to Augustus, and demanded Galerius promoted him. Galerius could not assuage either Maximinus or Constantine's anger, and so offered to call them both "sons of the Augusti".

In 310, Maximian, hungry for power, rebelled against his son-in-law while Constantine was campaigning against the Franks. He had been sent south to Arles with a contingent of Constantine's army, in preparation for any attacks by Maxentius in southern Gaul. Maximian announced that Constantine was dead, and resumed the imperial purple. He pledged a large donative to any troops who would support him as emperor, but most remained loyal to Constantine, and Maximian was compelled to leave. Constantine soon heard of the rebellion, abandoned his campaign against the Franks, and marched his army up the Rhine. With impressive speed, he moved from the front to the Saône, from the Saône to the Rhône, and from there on to southern Gaul, where he approached the fleeing Maximian at Massilia (Marseilles). Massilia was better capable of withstanding a long siege than Arles, but it made little difference: the loyal citizems of Massilia opened their rear gates to Constantine. Maximian was captured and reproved for his crimes. Constantine granted him some clemency, but Maximian's suicide was strongly encouraged. He committed suicide by hanging himself in July 310.

With Galerius' death in 311, the last ruler with enough authority interested in continuing the tetrarchy left the stage, and the system rapidly declined. In the struggle for power that ensued, Constantine allied himself with Licinius, while Maximinus approached Maxentius, who was still officially regarded as an usurper.

Early in 312, Constantine crossed the Alps with his army and attacked Maxentius. He quickly conquered Northern Italy in the battles of Turin and Verona and then moved on to Rome. There he defeated Maxentius in the Battle of the Milvian Bridge, which resulted in his becoming Western Augustus, or ruler of the entire Western Roman Empire. During this epic battle Constantine had his soldiers place on their shields what Christians believed was the labarum symbol, although there is a dispute between historians whether this design was of Christian or solar pagan origins, or whether it perhaps originated in the meteorological occurrences on the date thereof. In a dream the night before the battle, wrote the Christian apologist Lactantius, Constantine was told by God to paint the labarum on his soldiers' shields. Eusebius attributes another vision to Constantine, although historians have tended to doubt its veracity more than that of Lactantius. When Constantine was praying about noon, a sign appeared in the heavens above the Sun: a cross of light with the message "In this sign, you will conquer". He and his whole army were struck with amazement at the sign. Constantine was uncertain of the meaning of the sign, but in his sleep the Christian God came to him with the same sign, and commanded him to make a likeness of it, and use it as a safeguard.

Some have argued for a meteorological explanation of the vision, explaining it as either a "solar halo" or the tail of a meteor; but most historians have disputed either the details of the events or their very existence, arguing for an earlier or later conversion date and thereby avoiding the historiographic problems of miracles altogether. Some historians suggest that Lactantius' account, written from good sources soon after the battle, should be taken alone; that Constantine had the dream, but not the waking vision. In any event, the visions were part of Christians' common eschatological expectations in the period; beginning with the Gospel of Matthew and continuing on through the Didache, the Apocalypse of Peter, the Apocalypse of Elijah, the appearance of the "Sign of the Son of Man" in the heavens was a common motif preceding the Second Coming of Christ in Christian writings on the End Times. Lactantius and Constantine, in their other writings, show some awareness of this trend in eschatology.

In the following years, Constantine gradually consolidated his military superiority over his rivals in the crumbling Tetrarchy. In 313, he met Licinius in Milan to secure their alliance by the marriage of Licinius and Constantine's half-sister Constantia. During this meeting, the emperors agreed on the so-called Edict of Milan (which, in its surviving forms, was neither an edict nor issued in Milan), officially granting full tolerance to all religions in the Empire. The document had special benefits for Christians, legalizing their religion and granting them restoration for all property seized during Diocletian's persecution. It repudiates past methods of religious coercion, accepting religious plurality and using only general terms—"Divinity" and "Supreme Divinity", summa divinitas—avoiding any exclusive specificity. The conference was cut short, however, when news reached Licinius that his rival Maximinus Daia had crossed the Bosporus and invaded Licinian territory. Licinius departed and eventually defeated Maximinus, gaining control over the entire eastern half of the Roman Empire. Relations between the two remaining emperors deteriorated, though, and either in 314 or 316, Constantine and Licinius fought against one another in the war of Cibalae, with Constantine being victorious. They clashed again in the Battle of Campus Ardiensis in 317, and agreed to a settlement in which Constantine's sons Crispus and Constantine II, and Licinius' son Licinianus were made caesars.

In the year 320, Licinius reneged on the religious freedom promised by the Edict of Milan in 313 and began another persecution of the Christians. It became a challenge to Constantine in the west, climaxing in the great civil war of 324. Licinius, aided by Goth mercenaries, represented the past and the ancient faith of Paganism. Constantine and his Franks marched under the Christian standard of the labarum, and both sides saw the battle in religious terms. Supposedly outnumbered, but fired by their zeal, Constantine's army emerged victorious in the battles of Adrianople, the Hellespont, and at Chrysopolis. With the defeat and death of Licinius a year later (he was accused of plotting against Constantine and executed), Constantine became the sole emperor of the Roman Empire.

Licinius' defeat represented the passing of old Rome, and the beginning of the role of the Eastern Roman Empire as a center of learning, prosperity, and cultural preservation. Constantine rebuilt the city of Byzantium, and renamed it Nova Roma (New Rome) and issued special commemorative coins in 330 to honour the event. He provided Nova Roma with a Senate and civic offices similar to those of Rome. The new city was protected by the alleged True Cross, the Rod of Moses and other holy relics, though a cameo now at the Hermitage Museum also represented Constantine crowned by the tyche of the new city. The figures of old gods were replaced and often assimilated into Christian symbolism. On the site of a temple to Aphrodite was built the new Church of the Holy Apostles. Generations later there was the story that a Divine vision led Constantine to this spot, and an angel no one else could see, led him on a circuit of the new walls. After his death, his capital was renamed Nova Roma Constantinopolitana (Constantinople in English, "Constantine's City").

On some date between May 15 and June 17 326, Constantine had his eldest son Crispus seized and put to death by "cold poison" at Pola (Pula, Croatia). In July, Constantine had his wife, the Empress Fausta, killed at the behest of his mother, Helena. Fausta was hurled into baths of boiling water, and left to suffocate. Their names were wiped from the face of many inscriptions, references to their lives in the literary record were erased, and the memory of both was condemned. Eusebius, for example, edited praise of Crispus out of later copies of his Historia Ecclesiastica, and his Vita Constantini contains no mention of Fausta or Crispus at all. Few ancient sources are willing to discuss possible motives for the events; those few that do offer unconvincing rationales, are of later provenance, and are generally unreliable. At the time of the executions, it was commonly believed that the Empress Fausta was either in an illicit relationship with Crispus, or was spreading rumors to that effect. A popular myth arose, modified to allude to Hippolytus–Phaedra legend, with the suggestion that Constantine killed Crispus and Fausta for their immoralities. One source, the largely fictional Passion of Artemius, probably penned in the eighth century by John of Damascus, makes the legendary connection explicit. As an interpretation of the executions, the myth rests on only "the slimmest of evidence": sources that allude to the relationship between Crispus and Fausta are late and unreliable, and the modern suggestion that Constantine's "godly" edicts of 326 and the irregularities of Crispus are somehow connected rests on no evidence at all.

The historian Patrick Guthrie has postulated that the execution was made to lessen the risk of anarchy: Crispus was talented, but illegitimate; his survival would threaten the rule of Constantine's legitimate heirs; Constans, Constantius, and Constantine the Younger. Constantine, having risen to power through the collapse of the Tetrarchy, was well-aware of what such a period would look like. Guthrie's argument, however, was "ably" refuted in a paper by H.A. Pohlsander, who noted that Constantine's appointment of Crispus to the rank of Caesar had already proven his eligibility for the seat of the Augusti, and Constantine, being illegitimate himself, would not necessarily have seen illegitimacy as bar to the Imperial seat. Many scholars, in fact, dispute whether the two were illegitimate at all, leaving both argument and counter-argument seriously flawed.

Eusebius's account in book four of the Vita Constantini, which had previously been a "series of random and repetitious observations" spanning twenty years of time, returns to a chronological narrative in 335: the year of Constantine's tricennalia. It was an event marked by the Council of Tyre and the dedication of the Church of the Resurrection in Jerusalem, just as the Council of Nicaea had marked his bicennalia. Constantine was still sound in body and mind, and he continued to write and argue until the end of his life, but men began to take advantage of his generosity; Constantine, Eusebius wrote, was "forced into conduct unworthy of himself" by unruly persons, especially those who called themselves "Christian". At some date between 324 and 337, Constantine wrote a letter to the Persian king Shapur II, asserting that Iran's subjection to Christ was a foreordained fact. Constantine's rule had become seemingly universal. One priest pronounced that Constantine was not only chosen by God to rule over all men on Earth, but would also rule alongside the Son of God in the life to come. Eusebius records the arrival of Indian ambassadors at Constantine's court, with gifts of jewels and exotic beasts, in these years, noting thus that Constantine's sovereignty extended "even to the Indian Ocean, and that the princes of the land of the Indians ... acknowledged him as emperor and king." Such bold proclamations formed part of the intellectual culture preceding the coming conflict with Persia.

Eusebius account of the Persian conflict begins with reports of stirrings among the "barbarians of the East". Constantine, observing that he had not yet achieved a victory over the Persians, then decided to conduct an expedition against them. He mobilized his legions, and announced the plan to a number of his bishops, so that they might provide for the divine worship of the mission. Constantine constructed a tent of embroidered linen on the model of a church, as Moses had done in the wilderness. It was designed to be carried about, so that he might have a house of prayer ready in even the most desert regions. He set out from Constantinople with his triremes, set to shore at Soteropolis/Pythia, and there took the waters. But plans for war were then abandoned, because, in the words of Socrates of Constantinople, "it had already been extinguished through fear of the king [Constantine]". The church historian Gelasius of Cyzicus claimed that the plan was abandoned for the sake of Iranian Christians.

The rhetor Libanius writes of Persian re-armament and Persian hostility, contradicting Eusebius's account of an aggressive Constantine. In Libanius's version, the Persians had been preparing for a renewed offensive against Rome in response to the loss of those Western territories that were ceded to the Romans in 298. They had sent embassies and gifts in the meantime as a means of disguising their hostile intentions. The Persians realized that their defeat was the result of their inferior weaponry, and so set themselves on a comprehensive re-armament program, involving their whole adult male population. The Persians were handicapped, however, by insufficient supplies of iron ore. Shapur sent an embassy to Constantine's court, requesting permission to import iron from Roman lands, using renewed barbarian invasions as pretext. Constantine granted the Persians' request, because, although fully aware of their deceit, he wished his sons to have enemies worthy enough to fight against. The Persians, now rich with iron, introduced the mailed cavalry, which rode with both rider and horse heavily armored. A second Persian embassy was then sent to Constantine's court, demanding the cession of Roman territory in exchange for continued peace, but was angrily rejected for its arrogance and presumption. Constantine mobilized his armies and began to move against Persia, but died in Nicomedia, leaving the laurels of 'barbarian victories' to his sons.

Eusebius's account of the war is incomplete; it breaks off just as Constantine begins to plan with his advisors. A lacuna of half a page exists in all the surviving manuscripts of Eusebius's Vita, and the surviving parts of the Vita have no description of the conduct of the Persian war. There are suggestions that Eusebius, and whoever was reponsible for the lacuna, was attempting to conceal the incomplete commission of the Persian war, a tale that had been taken up by unscrupulous later pagans as a means of deriding Constantine's legacy. Libanius's account, too, is not universally accepted as truthful: Hans-Ulrich Wiemer, writing in The Classical Quarterly, argues that Libanius's account reproduces a story disseminated by Constantius, noting that the tale seems founded on official views, because the tale contains, within its fictional framework, some reliable statements of fact—that Highland Iran is lacking in iron ore, and that the export of metals was then forbidden— and, finally, that the story served to justify the foreign and military policies of Constantius, by demonstrating that he was not responsible for the outbreak of war, nor for the failures of his troops, since Persian military superiority had been assured by the misguided policies of Constantine.

Eusebius's account resumes following the abortive Persian campaign, with Constantine set about building a martyrion for the apostles in Constantinople, and, within it, a final resting-place for himself. In the course of one Feast of Easter, Constantine fell seriously ill. He left Constantinople for the hot baths near his mother's city of Helenopolis (Altinova), on the southern shores of the Gulf of İzmit. There, in a chuch his mother built in honor of Lucian the Apostle, he prayed, and there he realized that he was dying. Seeking purification, he became a catechumen, and attempted a return to Constantinople, making it only as far as a suburb of Nicomedia. He summoned the bishops, and told them of his hope to be baptized in the River Jordan, where Christ was written to have been baptized. He requested the baptism right away, promising to live a more Christian life should he live through his illness. The bishops, Eusebius records, "performed the sacred ceremonies according to custom". He chose the Arianizing bishop Eusebius of Nicomedia as his baptizer. Constantine died soon after at a suburban villa called Achyron, on the last day of the fifty-day festival of Pentecost directly following Easter, on May 22 337.

Although Constantine's death follows the conclusion of the Persian campaign in Eusebius's account, most other sources report his death as occurring in its middle. Emperor Julian, writing in the mid-350s, observes that the Sassanians escaped punishment for their ill-deeds, because Constantine died "in the middle of his preparations for war". Similar accounts are given in the Origo Constantini, an anonymous document composed while Constantine was still living, and which has Constantine dying in Nicomedia; the Historiae abbreviatae of Sextus Aurelius Victor, written in 361, which has Constantine dying at an estate near Nicomedia called Achyrona while marching against the Persians; and the Brevarium of Eutropius, a handbook compiled in 369 for the Emperor Valens, which has Constantine dying in a nameless state villa in Nicomedia. From these and other accounts, some have concluded that Eusebius's Vita was edited to defend Constantine's reputation against what Eusebius saw as a less congenial version of the campaign.

In postponing his baptism, he followed one custom at the time which postponed baptism until old age or death. Following his death, his body was transferred to Constantinople and buried in the Church of the Holy Apostles there. He was succeeded by his three sons born of Fausta, Constantine II, Constantius II and Constans. A number of relatives were killed by followers of Constantius. He also had two daughters, Constantina and Helena, wife of Emperor Julian.

Constantine is perhaps best known for being the first Christian Roman Emperor. His reign was a turning point for the Christian Church. In 313 Constantine announced toleration of Christianity in the Edict of Milan, which removed penalties for professing Christianity (under which many had been martyred in previous persecutions of Christians) and returned confiscated Church property. Though a similar edict had been issued in 311 by Galerius, then senior emperor of the Tetrarchy, Constantine's lengthy rule, conversion, and patronage of the Church redefined the status of Christianity in the empire.

Scholars debate whether Constantine adopted his mother St. Helena's Christianity in his youth, or whether he adopted it gradually over the course of his life. Constantine was over 40 when he finally declared himself a Christian. Writing to Christians, Constantine made clear that he believed he owed his successes to the protection of the Christian High God alone. Throughout his rule, Constantine supported the Church financially, built various basilicas, granted privileges (e.g. exemption from certain taxes) to clergy, promoted Christians to high ranking offices, and returned property confiscated during the Great Persecution of Diocletian. His most famous building projects include the Church of the Holy Sepulchre and Old Saint Peter's Basilica. The reign of Constantine established a precedent for the position of the Christian Emperor in the Church; Constantine considered himself responsible to God for the spiritual health of his subjects, and thus he had a duty to maintain orthodoxy. For Constantine, the emperor did not decide doctrine - that was the responsibility of the bishops - rather his role was to enforce doctrine, root out heresy, and uphold ecclesiastical unity. The emperor ensured that God was properly worshipped in his empire; what proper worship consisted of was for the Church to determine.

In 316, Constantine acted as a judge in a North African dispute concerning the heresy of Donatism. More significantly, in 325 he summoned the Council of Nicaea, effectively the first Ecumenical Council (unless the Council of Jerusalem is so classified), to deal mostly with the heresy of Arianism.

Constantine also enforced the prohibition of the First Council of Nicaea against celebrating Easter on the day before the Jewish Passover (14 Nisan) (see Quartodecimanism and Easter controversy).

Constantine instituted several legislative measures impacting on Jews. They were forbidden to own Christian slaves or to circumcise their slaves. Conversion of Christians to Judaism was outlawed. Congregations for religious services were restricted, but Jews were allowed to enter Jerusalem on Tisha B'Av, the anniversary of the destruction of the Temple.

Coins struck for emperors often reveal details of their personal iconography. During the early part of Constantine's rule, representations first of Mars and then (from 310) of Apollo as Sun god consistently appear on the reverse of the coinage. Mars had been associated with the Tetrarchy, and Constantine's use of this symbolism served to emphasize the legitimacy of his rule. After his breach with his father's old colleague Maximian in 309–310, Constantine began to claim legitimate descent from the third century emperor Marcus Aurelius Claudius Gothicus (Claudius II), the hero of the Battle of Naissus (September, 268).



Gothicus had claimed the divine protection of Apollo-Sol Invictus. Constantine also promoted an association of himself with Sol Invictus, which was the last deity to appear on his coinage. The reverses of his coinage were dominated for several years by his "companion, the unconquered Sol" — the inscriptions read SOLI INVICTO COMITI. The depiction represents Apollo with a solar halo, Helios-like, and the globe in his hands. In the 320s Constantine has a halo of his own. There are also coins depicting Apollo driving the chariot of the Sun on a shield Constantine is holding. Elements of this association remained even after Constantine's famous conversion to Christianity in 312. Thereafter, Christian symbolism, albeit ambiguous in some instances, began to appear in Imperial iconography. A coin of ca 312, for example, shows the chi-rho, the first two letters of the name of Christ in Greek, on a helmet Constantine is wearing.



A continuation of the iconographic precedent can be seen in the larger eye of the coin portrait. This suggests a more fundamental shift in official images. Beginning in the late third century, portraits began to become less realistic and more idealized. The Emperor as Emperor, not merely as any particular individual, is of primary importance. The most common characteristics of this style are the broad jaw and cleft chin. The large staring eyes will loom larger as the fourth century progresses: compare the early fifth century silver coinage of Theodosius I, or the bust of Arcadius.

Constantine respected cultivation and Christianity, and his court was composed of older, respected, and honored men. Leading Roman families that refused Christianity were denied positions of power, yet two-thirds of his top government was non-Christian.

From Pagan temples Constantine had his statue removed. The repair of Pagan temples that had decayed was forbidden. These funds were given to the favored Christian clergy. Offensive forms of worship, either Christian or Pagan, were suppressed. At the dedication of Constantinople in 330 a ceremony half Pagan and half Christian was performed, in the market place, the Cross of Christ was placed over the head of the Sun-God's chariot. There was a singing of hymns.

Constantine passed laws making the occupations of butcher and baker hereditary, and more importantly, supported converting the coloni (tenant farmers) into serfs — laying the foundation for European society during the Middle Ages.

Constantine's laws in many ways improved those of his predecessors, though they also reflect his more violent age. Some examples: *For the first time, girls could not be abducted (this may actually refer to elopements, which were considered kidnapping because girls could not legally consent to the elopement). *A punishment of death was mandated to anyone collecting taxes over the authorized amount. *A prisoner was no longer to be kept in total darkness, but must be given the outdoors and daylight. *A condemned man was allowed to die in the arena, but could not be branded on his "heavenly beautified" face, just on the feet (because God made man in His image). *Slave "nurses" or chaperones caught allowing the girls they were responsible for to be seduced were to have molten lead poured down their throats. *Gladiatorial games were ordered to be eliminated in 325, although this had little real effect. *A slave master's rights were limited, but a slave could still be beaten to death. *Crucifixion was abolished for reasons of Christian piety, but was replaced with hanging, to show there was Roman law and justice. *Easter could be publicly celebrated. * A Sunday law enforcing its public observation as a day of rest was enacted.

Although he earned his honorific of "The Great" (= "Μέγας" in greek) from Christian historians long after he had died, he could have claimed the title on his military achievements and victories alone. In addition to reuniting the Empire under one emperor, Constantine won major victories over the Franks and Alamanni in 306–308, the Franks again in 313–314, the Visigoths in 332 and the Sarmatians in 334. In fact, by 336, Constantine had actually reoccupied most of the long-lost province of Dacia, which Aurelian had been forced to abandon in 271. At the time of his death, he was planning a great expedition to put an end to raids on the eastern provinces from the Persian Empire.

The Byzantine Empire considered Constantine its founder and also the Holy Roman Empire reckoned him among the venerable figures of its tradition. In both East and West, Emperors were sometimes hailed as a "new Constantine". At the court of Charlemagne, the selected use of monumental Constantinian forms lent expression to conception of Charlemagne as Constantine's successor and equal. Constantine acquired a mythic role as a warrior against "heathens", a feature parodied in the fifteenth-century Chronicle of Pseudo-Turpin. The motif of the Romanesque equestrian, the mounted figure in the posture of a triumphant Roman emperor, came to be used as a visual metaphor in statuary in praise of local benefactors. The name "Constantine" itself enjoyed renewed popularity in western France in the eleventh and twelfth centuries. Most Eastern Christian churches consider Constantine a saint (Άγιος Κωνσταντίνος, Saint Constantine). In the Byzantine Church he was called isapostolos (Ισαπόστολος Κωνσταντίνος)—an equal of the Apostles.

Latin Rite Catholics of the Middle Ages considered it inappropriate that Constantine was baptized only on his death-bed and by a bishop of questionable orthodoxy, viewing it as a snub to the authority of the Papacy. Hence, by the early fourth century, a legend had emerged that Pope Sylvester I (314–35) had cured the pagan Emperor from leprosy. According to this legend, Constantine was soon baptized, and began the construction of a church in the Lateran Palace. In the eighth century, most likely during the pontificate of Stephen II (752–7), a document called the "Donation of Constantine" first appeared, in which the freshly converted Constantine hands the temporal rule over "the city of Rome and all the provinces, districts, and cities of Italy and the Western regions" to Stephen and his successors. In the High Middle Ages, this document was used and accepted as the basis for the Pope's temporal power, though it was denounced as a forgery by Emperor Otto III and lamented as the root of papal worldliness by the poet Dante Alighieri. The 15th century philologist Lorenzo Valla proved the document was indeed a forgery.

Because of his fame and his being proclaimed Emperor on the territory of Great Britain, Constantine was later also considered a British King. In the 11th century, the English writer Geoffrey of Monmouth published a fictional work called Historia Regum Britanniae, in which he narrates the supposed history of the Britons and their kings from the Trojan War, King Arthur and the Anglo-Saxon conquest. In this work, Geoffrey claimed that Constantine's mother Helena was actually the daughter of "King Cole", the mythical King of the Britons and eponymous founder of Colchester. A daughter for King Cole had not previously figured in the lore, at least not as it has survived in writing, and this pedigree is likely to reflect Geoffrey's desire to create a continuous line of regal descent. It was indecorous, Geoffrey considered, that a king might have less-than-noble ancestors. Geoffrey also said that Constantine was proclaimed "King of the Britons" at York, rather than Roman Emperor.

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*Ammianus Marcellinus *Arch of Constantine, triumphal arch to the victory at Milvian Bridge. *Christianity *Colossus of Constantine *Constantine I And Christianity *Constantinian shift *Donation of Constantine *Donatist

*The Edict of Milan AD 313 *Letters of Constantine: Book 1, Book 2, & Book 3 *Encyclopaedia Britannica, Constantine I *RomanEmperors.org Vita of Constantine; with bibliography *Ammianus Marcellinus on-line project *12 Byzantine Rulers by Lars Brownworth of Stony Brook School (grades 7-12). 40 minute audio lecture on Constantine. *Constantine I in the 1911 Encyclopædia Britannica *Constantine the Great A site about Constantine the Great and his bronze coins emphasizing history using coins, with many resources including reverse types issued and reverse translations. *House of Constantine bronze coins Illustrations and descriptions of coins of Constantine the Great and his relatives. *BBC North Yorkshire's site on Roman York, Yorkshire and Constantine the Great

Valerius Aurelius Constantinus, Gaius Constantine the Great