Constantine was the senior figure in the new dyarchy. He was probably born around 273 at Naissus (Niš) in Lower Moesia, the eldest son of Constantius by Helena, reputedly a woman of humble origin. In later years Constantine was to found a city named after her at Drepanum near Nicomedia, and the mistaken belief became current that this had been her birthplace. More likely she had been born, like Constantius, in the Danubian province of Dacia Ripensis. Several sources indicate that before he rose to prominence in 305 Constantine had served as a military officer, a tribunus, in the service of Diocletian and Galerius. The anonymous Latin account of his career, written soon after Constantine's death in 337, describes him as being held hostage (Origo Constantini imperatoris, Anon. Val. 2), but this assessment echoed Constantine's own propaganda, which was designed to distance him from the anti-Christian rulers Diocletian and Galerius and misrepresented the real situation. In fact he had certainly served for many years both at court and on campaigns led by Galerius, as would have been natural for the son of Constantius, a member of the ruling imperial college.26 The same source also declares that we has a courageous soldier, and this is not in question.
The turbulent events of 305 to 312 proved the making of Constantine. Three traditional strands of Roman political life were interwoven in the struggles of these years: dynastic claims to power, the support of the armies, and the harnessing of religious propaganda. The artificial imposition of the tetrarchic system devised by Diocletian proved weaker than dynastic claims when power was transferred to a new ruler. Diocletian himself had implicitly recognized this fact when he used marriage connections to bind the Caesars, Constantius and Galerius, into the ruling coalition. The father–son combinations of Constantius and Constantine, and Maximianus and Maxentius were resilient and politically effective. Galerius compromised with Constantine, admitting him to the imperial college in 306. Maxentius proved his mettle by six effective years of defiance from his base at Rome. The panegyric of 310, delivered in praise of Constantine shortly after the downfall of Maximianus in 310, puts forward a manifesto for the primacy of familial claims to power:
I will begin with your origin, because very many people up till now perhaps do not know it, but those who esteem you most do. The relationship of a grandson flows down to you from that divine Claudius, who first restored the lax and lost discipline of the Roman empire, and destroyed in land and sea battles huge bands of Goths who had poured forth from the gaping jaws on the Pontus and the mouths of the Danube.…The ancient prerogative of the imperial house advanced your own father, so that you should stand at the highest step, supreme over the fate of human affairs, the third emperor after two members of your family had been princes. Among all the sharers of your majesty, you have this status above all, Constantine, that you were born an emperor, and so great is the nobility of your origin, that the grant of empire added nothing to your honour. (Pan. Lat. VII , 2)
The flimsy claim that Constantine was in fact the grandson of the emperor Claudius Gothicus appears here for the first time.27 It was designed to secure Constantine's position as the dominant emperor against the aspirations of Galerius, Licinius, and Maximinus, who could boast no such lineages, and against Maxentius, who had only been preceded by his father as Augustus. By this time it must have been clear to all that the aim of the tetrarchy, to divorce imperial power from family succession, was dead. The rivals for power played the old game of dynastic politics for all it was worth.
The emperors also depended on the support of their troops. Backing from the praetorians, who had certainly been induced by the prospect of substantial donatives, impelled Maxentius' bid at Rome, and he also relied on the influence of his father Maximianus to win over troops from Severus, whose position was vulnerable to this dynastic challenge. Maxentius' own hold over the praetorians, however, proved sufficient to enable him to resist his father, when Maximianus attempted to supplant his son and resume power himself. Constantine meanwhile, having been acclaimed by his father's army in 306, had consolidated his popularity with them by throwing the defeated kings of the Alemanni and the Franks to the beasts in the arena.28 Civil wars aroused hopes of rich pickings; the prizes at stake were not modest plunder from barbarian villages, but the substantial wealth and lands of Roman rivals. It is fair to guess that military loyalty to a commander was never stronger than in civil wars fought against their own kind. A telling document in this context is the bronze inscription found at Brigetio in Pannonia, containing a letter issued at Serdica in June 311 by Licinius. A second copy of this text has been recovered in Bulgaria. It offered the soldiers of the Balkan armies a huge reduction in their tax liabilities, by allowing them exemption for up to five capita (heads) in their households, when these were assessed for their normal obligations to the military annona, in place of the usual two. The purpose was to secure their loyalty in the forthcoming war with Maximinus, who was simultaneously attempting to seal the loyalty of his eastern subjects by targeting tax reductions on those who denounced the Christians.29
There is a striking parallel to this offer in a constitution of Constantine which probably dates to 320, the period of Constantine's own struggle with Licinius. The emperor entered the imperial army headquarters, amid the acclamations of his military prefects, tribunes, and other leading figures of the regime. He was confronted by veterans, due for discharge from service, who presented a demand: “Constantine Augustus, to what purpose have we been made veterans if we have no special grant of imperial privileges?” As the emperor made it clear that he was willing to hear their petition, a spokesman made the specific demand that veterans be exempted from providing compulsory public services. Constantine, in what was evidently a stage managed gesture, granted the request: “Be it known that it has now just been conceded to all veterans by my munificence that no one of them shall be compelled by law to perform a compulsory municipal service.”30
The power struggles of the early fourth century were played out in a growing atmosphere of religious rivalry. Religious reform had been the bedrock of the new order imposed by Diocletian. World dominance was secured under the guidance of the two gods Jupiter and Hercules. This religious ideology was ubiquitous: The porticos of the theater of Pompeius at Rome were renamed the porticus Iovia and the porticus Herculia and dedicated respectively to the genii of Iovius Augustus (Diocletian) and Herculius Augustus (Maximianus); the gates of Grenoble were labeled porta Iovia and porta Herculia.31 It is important to emphasize that although this new state religion gave prominence to traditional gods, it assumed a radically different form from earlier official cultic activity at Rome. There may even have been influence from Christian ideas, due to the similarity between Christian belief in God the Father and God the Son, and the roles assigned to Jupiter as rector caeli, and Hercules as pacator terrarum.32
The promotion of new Roman gods was accentuated by the demonizing of foreign enemies. The clearest example of this is the letter which was sent to a proconsul of Africa about how to deal with the sect of the Manichees, perhaps in 297. The introduction is highly illuminating for the religious temper of the tetrarchic period. “The language is filled with significant words to denote ancient Roman virtue and new Persian vice.”33 It argued that in times of peace the wicked tended to introduce ignorant and foolish doctrines, threatening the moral order. Established religion must not be criticized by a new one, and it was a most serious matter to tamper with what had been laid down since antiquity. The emperors had a responsibility to punish those who propagandized new sects (Mosaicarum et Romanarum Legum collectio XV.3; trans. in Stevenson, New Eusebius 267 no. 236).
The legislation of this period included a law against eastern groups which allowed incestuous marriages (CJust. 5.5.2). These measures provide a ready context for understanding the most famous of Diocletian's religious actions, the decision taken in 303 to outlaw Christianity and to set in motion what has become known as the Great Persecution. This received so much attention from Christian writers, especially Lactantius and Eusebius, that it is easy to set these events out of proportion. Lactantius, always given to highlight a colorful incident or anecdote, identified the origin of the persecution at the occasion of a ritual, during which the haruspices (priestly diviners) were unable to detect the usual favorable signs in the entrails of sacrificial victims, and blame was cast on Christians who were present at the ceremony.34 He claimed that Diocletian, under the strong influence of Galerius, who had in turn been swayed by his rabidly pagan mother, consulted first his court and senior military officers, and then the oracle of Apollo at Didyma, before issuing an edict on February 23, 303, the Roman festival of Terminalia, from the imperial residence at Nicomedia. Although the wording of the edict is not preserved, its terms resembled the outlawing of the Manichees. Churches were to be destroyed, and copies of the scriptures sought out and burned. Christians were to be stripped of any rank or honor they held, and were legally downgraded, to be liable to torture. Since they would be required to swear a pagan oath, they were effectively denied the right to take any action in a Roman court. The main church in Nicomedia, which stood provocatively in full view of the palace, was razed to the ground by the praetorian guard, but the effects of this measure were initially relatively limited.
Thanks to the Christian writers we can follow the dissemination of the edict through the empire in a way that is impossible for other imperial legislation. Letters were sent to provincial authorities in 303 and 304 which urged them to play an active role in arresting and imprisoning clergy. Later sources, concerned with the origins of the Donatist controversy, provide a vivid account of the hunting down and handing over of scriptures to be burnt in the African city of Cirta.35 In effect everything depended on the zeal and enthusiasm of the Roman authorities locally. This applied to the emperors themselves, as well as to provincial governors. The Christian tradition is unanimous that Constantius in Trier did little to trouble the Christians. Lactantius says he confined himself to destroying some churches, but even this was denied by Eusebius.36 Outside Africa there is almost no trace of persecution in the western provinces. In any case the edict was reluctantly rescinded by Galerius on the eve of his death in May 311, apparently following similar actions taken by Constantine as early as 306, and by Maxentius perhaps in 308.37
In the East the most energetic anti-Christian action came from the new emperor Maximinus, whose actions must have been closely observed (although they may have been exaggerated) by Eusebius, who was living in Caesarea, the emperor's residence from 306 to 308. After the death of Galerius in 311, Maximinus contrived to persuade eastern communities to send him petitions demanding that persecution be carried on with full vigor, and in response to these propounded a doctrine of pagan belief, which reasserted the powers of the traditional gods and their influence on world affairs:
Who is so obtuse as not to see that the benevolent concern of the gods is responsible for the fertility of the earth, for keeping the peace, and defeating unrighteous enemies, for curbing storms at sea, tempests and earthquakes, which have only occurred when the Christians with their ignorant and futile beliefs, have come to afflict almost the whole world with their shameful practices.38
We must place the most dramatic and far-reaching religious event of the early fourth century, Constantine's conversion to Christianity, in this context. On the eve of the decisive battle with Maxentius Constantine was convinced that a solar apparition that he had experienced should be interpreted as a promise of victory from the God of the Christians. Armed with this new conviction, and placing, we are told, the sign of the cross on the shields of his soldiers, he led his outnumbered troops to a bloody but decisive victory at the Milvian bridge over the river Tiber. The nature of his vision and conversion are discussed on pp. 278–85. It is generally acknowledged that there was a close affinity between the Christianity which Constantine endorsed in 312 and contemporary solar worship. The nature of his vision suggests that at the decisive moment of his imperial career, Constantine's belief in a supreme solar deity and belief in the Christian God were virtually convergent.
After the twin victories over Maxentius and Maximinus in 312 and 313, the relationship between the victors was uneasy and strained. The bond between the two Augusti was symbolically forged by the marriage of Constantine's sister Constantia to Licinius. Licinius was now Augustus in the East but also in effective control of most of the Balkan region.
Constantine's personal ambition far outweighed his collegial instincts, and were spurred when his second wife Fausta gave birth to a son, Constantinus, in spring 316. Between October 316 and January 317 he had defeated Licinius' forces first at Cibalae in Pannonia and then near Adrianople in Thrace. On March 1, 317, a new pact was made which confirmed Constantine and Licinius as Augusti, and appointed three Caesars: Constantine's sons Crispus (by his first marriage) and Constantinus, and Licinius' own infant son born to Constantia in 315, also called Licinius. The boundary between eastern and western rulers was set on the Thracian frontier. Constantine now controlled the entire empire as far as his own birthplace, Naissus. In the following years Fausta provided her husband with a quiverful of dynastic ammunition: Constantius, born in 317, a daughter Constantina, Constans born in 320 or 323, and another girl, Helena (Diagram 3.2). After 317 Constantine consolidated his power-base in Illyricum, and in 324 was ready for a final reckoning. Starting from Thessalonica, he defeated Licinius' troops at Adrianople in July and besieged Byzantium. His victory came at a land and sea battle at Chrysopolis on the Bosporus, followed soon after by Licinius' surrender at Nicomedia. Before the end of the year Constantine proclaimed the foundation of a new city at Byzantium, which was to bear his own name, Constantinople, and by spring 325 both Licinius and his son had been put to death in Thessalonica. The way was thus opened for the final phase of Constantine's reign.
Diagram 3.2 The Constantinian dynasty
From 324 until his death in 337 Constantine was sole Augustus. His second and third sons by Fausta, Constantius and Constans, were promoted to the rank of Caesar in 324 and 333. Meanwhile Crispus was executed in 326, accused perhaps of treason or of forming an adulterous relationship with his stepmother Fausta, and Fausta herself perished soon afterwards, apparently suffocated to death on the emperor's orders. The sources predictably provide divergent accounts of these sensational and sinister imperial secrets, which significantly damaged Constantine's posthumous reputation.39 The pagan historian Zosimus, who paints an unrelentingly hostile picture of Constantine, alleged that the emperor's conversion resulted from these events, as the Christians were the only sect that could offer him absolution for his crimes, through the rite of baptism, which in Constantine's case was deferred until his death bed.40
After the defeat of Licinius Constantine continued an aggressive frontier policy, designed to secure the Danube for Rome and to subordinate barbarians living north of the river. Stone bridges were built across the Rhine, at Cologne in 310 and across the Danube at Oescus in 328, protected in each case by forts on the north banks of the rivers. The purpose of the bridge at Cologne is illuminated by a contemporary panegyric:
Furthermore, by building the bridge at Agrippinensis you defy the remnants of the defeated tribe and compel them never to abandon their fears but to be in constant terror, and to keep outstretched their hands in submission. However, you are doing this more for the glory of your empire and to embellish the frontier, than to create an opportunity to cross into enemy territory whenever you wish.…(5) Certainly it brought you at its inception the submission of the enemy, who came in supplication for peace and brought well born hostages. So no one can doubt what they will do when the bridge is complete, if they are so servile when it is only just started. (Pan. Lat. [VI], 13.1–5, trans. Rodgers and Nixon)
These remarks make clear that the bridges were not designed to further extensive campaigns across the riverine boundaries of the empire. They made a conspicuous statement of Roman power, but also enabled traffic to pass across the frontier.
Christian sources show that Constantine was heavily engaged with the affairs of the church between 312 and the fall of Licinius. The compact at Milan in 313 proclaimed religious toleration for all, but particularly favored the Christians, since it brought a definitive end to the persecution (see p. 260). More than that, it provided both for the restoration of Christian property, and for those who had obtained possessions confiscated from Christians to be compensated at the state's expense.
Constantine was at once involved in the problem of the Donatists in Africa. The issue was quite simply to establish which was the official universal church in the province. A complicated feud had developed between a rigorist group, whose members reckoned that all who had compromised during the persecution were traitors to the church, and those who took a less severe line. The consecration of Caecilian as bishop of Carthage, probably in early 312, was challenged by the Donatist faction. Apart from the deeply held principle, there were material matters at issue, notably which party should benefit from privileges and imperial benefactions to the church (Eusebius, HE 10.5–7). In one of his letters Constantine denounced the Donatists as persons of unstable mind. But when they appealed, they received a remarkably even-handed reply from the emperor. A schism was to be avoided at all costs (see pp. 302–5).
By engaging with the Donatist dispute Constantine began to formulate a new view of his own responsibilities for religious affairs, and this was the first step towards a new style of Christian imperial rule. He saw himself as responsible to God for the unity and harmony of the earthly kingdom which he ruled:
What greater obligation is imposed on me by my own intent and the bounty of my sovereign, than that, dispelling errors and cutting short all rashness, I should bring it about that everyone displays true piety, simple concord and the worship fitting for God Almighty. (Optatus, app. 7.34a, trans. Edwards)
Constantine now began, unsystematically, to accommodate the church and its personnel within the wider institutions of the empire. He exempted clerics from civic liturgies (CTh. 1.16.1–2) and from taxation (CTh. 16.2.10). To balance this generosity, he also excluded rich persons from holding clerical office (CTh. 16.2.6). He gave bishops rights of jurisdiction under Christian law between Christian litigants (CTh. 1.27.1  and Constitutiones Sirmondianae 1 ), and rescinded the penalties placed by Roman laws on celibacy or on childless couples, thus endorsing the Christian reverence for celibacy and virginity.41 Virtually from the moment of his conversion he began to endow church construction to further the worship of the Christian God. The great basilica of John Lateran was constructed at Rome between 312 and 315 on the site of a cavalry barracks, which had housed the equestrian bodyguard of Constantine's rival Maxentius. Further major church building followed at Rome, including the Basilica of Santa Croce in Gerusalemme, where Constantine's mother Helena was buried. Although large-scale engineering may have been started on the Vatican hill for the Church of Saint Peter, this was not completed until the middle of the fourth century (see p. 334). Imperially financed churches were naturally built in the newly created city of Constantinople, and at the holy places of Christ's birth and crucifixion in Palestine. Eusebius reports that bishops, like himself, received letters from Constantine encouraging them to build new churches or restore existing church buildings.42
Other legislative measures were more ambiguous. In 321 a law was issued to the effect that Sunday should be a rest-day for those working in cities, although country dwellers were allowed to work their fields (CJust. 3.12.2). Slaves could be manumitted, but other legal business was forbidden. Eusebius interpreted this as the designation of Sunday as the “Lord's Day,” a day of Christian prayer (VC 4.18.1), but in view of the blurred distinction, in Constantine's own perception, between sun worship and Christianity, the motivation behind this action was certainly not simply to promote Christian worship. Eusebius adds that Constantine instructed military units to address a prayer to the sun, to be acknowledged as the one god and bringer of victory to the emperor and his family (VC 4.20). This was similar to a prayer to the sun which Licinius had asked his own army to offer before their decisive battle with Maximinus in 313 (Lactantius, On the Deaths of the Persecutors 46). Constantine's measure would have been offensive to few, and made formal accommodation between pagan and Christian worship easier than it had been.
Religious antagonism was built into the final struggle with Licinius, but the doctrinal conflict between him and Constantine was clearly exaggerated in the context of the civil war between them (see pp. 259–60). In 325 Constantine adopted his most prominent role in ecclesiastical politics, when he arranged for the first ecumenical council to be convened at Nicaea. It was almost certainly at this gathering that he made his most famous statement relating to his own role as a religious, as well as a political, leader:
Hence it was not without reason that once, on the occasion of his entertaining a company of bishops, he let fall the expression that he himself too was a bishop, addressing them in my hearing with the following words: “You are bishops (episkopoi) whose jurisdiction is within the Church: I also am a supervisor (episkopos), ordained by God to overlook affairs outside the Church.” And truly his measures corresponded with his words; for he watched over all his subjects with an episcopal care, and exhorted them as far as he could to lead a godly life. (Eusebius, VC 4.24, trans. Stevenson [adapted])
The central point of this statement was that Constantine acknowledged his own responsibilities towards the non-Christian inhabitants of the Roman world. Although he was a Christian by passionate personal conviction, and promoted the interests of the church by many of his actions and decisions, he was also committed to the well-being of the empire as a whole (see p. 262).
Constantine's politics and the character of his reign have provoked passionate discussion and disagreements among historians, and this is as evident in recent as in earlier monographs and studies of the emperor. The terms of engagement over the last generation have to a large extent been defined by T. D. Barnes' seminal book, Constantine and Eusebius (1981), which presented a powerful and densely documented case for Constantine as a ruler whose decisions and actions were overwhelmingly guided by his Christian convictions, a perspective that is derived from the most extensive single source for his rulership, Eusebius' Life of Constantine. Historical scrutiny, both offering support for and challenging this assessment, has focused on central aspects of the emperor and his politics: the legislative activity of the Constantinian period, the religious allegiance of other leading political figures of the period, the relationship between the state and the Church, the significance of the creation of a new imperial capital at Constantinople. The credibility of the information contained in Eusebius' Life, and the emphasis that the Life places on Constantine's promotion of Christianity to the exclusion of almost all other aspects of his rulership, have repeatedly been called into question by Barnes' critics.43In the din of scholarly battle, it is extraordinarily refreshing to have new evidence, and this has been provided by the recent studies of Kevin Williamson, who has demonstrated that many of the epigrams of the pagan Greek writer Palladas were composed in Constantinople between c.325 and 335 and should be understood as the reaction during the foundation years of the new city of an educated Greek pagan, a Hellen, to the Christian agenda, which was being realized in political terms by Constantine after the defeat of Licinius. Constantine himself is not named, but identified as “the one whom God loves,” while Palladas and his pagan confrères could no longer deceive themselves about the triumph of the Christians. The world, their old world, had been turned on its head by the new ruler:
On the great wickedness of envy! A certain person hates the fortunate man whom God loves. Thus we are irrationally deceived by envy, and thus we are readily enslaved to folly. We Hellenes are men reduced to ashes, holding to our buried hopes in the dead; for everything has been turned on its head. (Palladas, Anth. Pal. 10. 90, trans. Wilkinson)
Palladas' viewpoint, as expressed in these epigrams, shows that the Eusebian view of Constantine was also shared by intellectual pagan contemporaries, and cannot be dismissed as the wishful thinking of an optimistic Christian propagandist.44