Remains of the luxurious residence palace of Mediana, erected by Constantine I near his birth town of Naissus
Flavius Valerius Constantinus, as he was originally named, was born in the city of Naissus, (today Niš, Serbia) part of the Dardania province of Moesia on 27 February, probably c. 272 AD. His father was Flavius Constantius and was born in the province of Moesia (later Dacia Ripensis), . Constantine probably spent little time with his father  who was an officer in the Roman army, part of the Emperor Aurelian’s imperial bodyguard. Being described as a tolerant and politically skilled man, Constantius advanced through the ranks, earning the governorship of Dalmatia from Emperor Diocletian, another of Aurelian’s companions from Illyricum, in 284 or 285. Constantine’s mother was Empress Helena, a woman of low social standing from Helenopolis of Bithynia. It is uncertain whether she was legally married to Constantius or merely his concubine. His main language was Latin, and during his public speeches he needed Greek translators.
Head from a statue of Diocletian
Bust of Maximian
In July 285 AD, Diocletian declared Maximian, another colleague from Illyricum, his co-emperor. 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. Maximian ruled in the West, from his capitals at Mediolanum (Milan, Italy) or Augusta Treverorum (Trier, Germany), while Diocletian ruled in the East, from Nicomedia (İzmit, Turkey). The division was merely pragmatic: the Empire was called “indivisible” in official panegyric, and both emperors could move freely throughout the Empire. In 288, Maximian appointed Constantius to serve as his praetorian prefect in Gaul. Constantius left Helena to marry Maximian’s stepdaughter Theodora in 288 or 289.
Diocletian divided the Empire again in 293 AD, appointing two Caesars (junior emperors) to rule over further subdivisions of East and West. Each would be subordinate to their respective Augustus (senior emperor) but would act with supreme authority in his assigned lands. This system would later be called the Tetrarchy. Diocletian’s first appointee for the office of Caesar was Constantius; his second was Galerius, a native of Felix Romuliana. According to Lactantius, Galerius was a brutal, animalistic man. Although he shared the paganism of Rome’s aristocracy, he seemed to them an alien figure, a semi-barbarian. On 1 March, Constantius was promoted to the office of Caesar, and dispatched to Gaul to fight the rebels Carausius and Allectus. In spite of meritocratic overtones, the Tetrarchy retained vestiges of hereditary privilege, and Constantine became the prime candidate for future appointment as Caesar as soon as his father took the position. Constantine went to the court of Diocletian, where he lived as his father’s heir presumptive.
In the East
Porphyry bust of Galerius
Constantine received a formal education at Diocletian’s court where he learned Latin literature, Greek, and philosophy. The cultural environment in Nicomedia was open, fluid, and socially mobile; in it, Constantine could mix with intellectuals both pagan and Christian. He may have attended the lectures of Lactantius, a Christian scholar of Latin in the city. Because Diocletian did not completely trust Constantius — none of the Tetrarchs fully trusted their colleagues — Constantine was held as something of a hostage, a tool to ensure Constantius’s best behavior. Constantine was nonetheless a prominent member of the court: he fought for Diocletian and Galerius in Asia and served in a variety of tribunates; he campaigned against barbarians on the Danube in 296 AD and fought the Persians under Diocletian in Syria (297 AD) as well as under Galerius in Mesopotamia (298–299 AD). By late 305 AD, he had become a tribune of the first order, a tribunus ordinis primi.
Constantine had returned to Nicomedia from the eastern front by the spring of 303 AD, in time to witness the beginnings of Diocletian’s “Great Persecution”, the most severe persecution of Christians in Roman history. In late 302, Diocletian and Galerius sent a messenger to the oracle of Apollo at Didyma with an inquiry about Christians. Constantine could recall his presence at the palace when the messenger returned, when Diocletian accepted his court’s demands for universal persecution. On 23 February 303 AD, Diocletian ordered the destruction of Nicomedia’s new church, condemned its scriptures to the flames, and had its treasures seized. In the months that followed, churches and scriptures were destroyed, Christians were deprived of official ranks, and priests were imprisoned.
It is unlikely that Constantine played any role in the persecution. In his later writings, he would attempt to present himself as an opponent of Diocletian’s “sanguinary edicts” against the “worshippers of God”, but nothing indicates that he opposed it effectively at the time. Although no contemporary Christian challenged Constantine for his inaction during the persecutions, it remained a political liability throughout his life.
On 1 May 305 AD, Diocletian, as a result of a debilitating sickness taken in the winter of 304–305 AD, announced his resignation. In a parallel ceremony in Milan, Maximian did the same. Lactantius states that Galerius manipulated the weakened Diocletian into resigning, and forced him to accept Galerius’ allies in the imperial succession. According to Lactantius, the crowd listening to Diocletian’s resignation speech believed, until the very last moment, that Diocletian would choose Constantine and Maxentius (Maximian’s son) as his successors. It was not to be: Constantius and Galerius were promoted to Augusti, while Severus and Maximinus Daia, Galerius’ nephew, were appointed their Caesars respectively. Constantine and Maxentius were ignored.
Bronze statue of Constantine I in York, England, near the spot where he was proclaimed Augustus in 306
Some of the ancient sources detail plots that Galerius made on Constantine’s life in the months following Diocletian’s abdication. They assert that Galerius assigned Constantine to lead an advance unit in a cavalry charge through a swamp on the middle Danube, made him enter into single combat with a lion, and attempted to kill him in hunts and wars. Constantine always emerged victorious: the lion emerged from the contest in a poorer condition than Constantine; Constantine returned to Nicomedia from the Danube with a Sarmatian captive to drop at Galerius’ feet. It is uncertain how much these tales can be trusted.
In the West
Marble bust of Constantine the Great from Stonegate, York
Constantine recognized the implicit danger in remaining at Galerius’s court, where he was held as a virtual hostage. His career depended on being rescued by his father in the west. Constantius was quick to intervene. In the late spring or early summer of 305 AD, Constantius requested leave for his son to help him campaign in Britain. After a long evening of drinking, Galerius granted the request. Constantine’s later propaganda describes how he fled the court in the night, before Galerius could change his mind. He rode from post-house to post-house at high speed, hamstringing every horse in his wake. By the time Galerius awoke the following morning, Constantine had fled too far to be caught. Constantine joined his father in Gaul, at Bononia (Boulogne) before the summer of 305 AD.
From Bononia they crossed the Channel to Britain and made their way to Eboracum (York), capital of the province of Britannia Secunda and home to a large military base. Constantine was able to spend a year in northern Britain at his father’s side, campaigning against the Picts beyond Hadrian’s Wall in the summer and autumn. Constantius’s campaign, like that of Septimius Severus before it, probably advanced far into the north without achieving great success. Constantius had become severely sick over the course of his reign, and died on 25 July 306 in Eboracum (York). Before dying, he declared his support for raising Constantine to the rank of full Augustus. The Alamannic king Chrocus, a barbarian taken into service under Constantius, then proclaimed Constantine as Augustus. The troops loyal to Constantius’ memory followed him in acclamation. Gaul and Britain quickly accepted his rule; Hispania, which had been in his father’s domain for less than a year, rejected it.
Constantine sent Galerius an official notice of Constantius’s death and his own acclamation. Along with the notice, he included a portrait of himself in the robes of an Augustus. The portrait was wreathed in bay. 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 put into a fury by the message; he almost set the portrait on fire. His advisers calmed him, and argued that outright denial of Constantine’s claims would mean certain war. Galerius was compelled to compromise: he granted Constantine the title “Caesar” rather than “Augustus” (the latter office went to Severus instead). Wishing to make it clear that he alone gave Constantine legitimacy, Galerius personally sent Constantine the emperor’s traditional purple robes. Constantine accepted the decision, knowing that it would remove doubts as to his legitimacy.
The portrait of Constantine on a Roman coin; the inscription around the portrait is “Constantinus Aug[ustus]”
Constantine’s share of the Empire consisted of Britain, Gaul, and Spain, and he commanded one of the largest Roman armies which was stationed along the important Rhine frontier. He remained in Britain after his promotion to emperor, driving back the tribes of the Picts and securing his control in the northwestern dioceses. He completed the reconstruction of military bases begun under his father’s rule, and he ordered the repair of the region’s roadways. He then left for Augusta Treverorum (Trier) in Gaul, the Tetrarchic capital of the northwestern Roman Empire. The Franks learned of Constantine’s acclamation and invaded Gaul across the lower Rhine over the winter of 306–307 AD. He drove them back beyond the Rhine and captured Kings Ascaric and Merogais; the kings and their soldiers were fed to the beasts of Trier’s amphitheatre in the adventus (arrival) celebrations which followed.
Public baths (thermae) built in Trier by Constantine, more than 100 metres (328 ft) wide by 200 metres (656 ft) long and capable of serving several thousand at a time, built to rival those of Rome
Constantine began a major expansion of Trier. He strengthened the circuit wall around the city with military towers and fortified gates, and he began building a palace complex in the northeastern part of the city. To the south of his palace, he ordered the construction of a large formal audience hall and a massive imperial bathhouse. He sponsored many building projects throughout Gaul during his tenure as emperor of the West, especially in Augustodunum (Autun) and Arelate (Arles). According to Lactantius, Constantine followed a tolerant policy towards Christianity, although he was not yet a Christian himself. He probably judged it a more sensible policy than open persecution and a way to distinguish himself from the “great persecutor” Galerius. He decreed a formal end to persecution and returned to Christians all that they had lost during them.
Constantine was largely untried and had a hint of illegitimacy about him; he relied on his father’s reputation in his early propaganda, which gave as much coverage to his father’s deeds as to his. His military skill and building projects, however, soon gave the panegyrist the opportunity to comment favourably on the similarities between father and son, and Eusebius remarked that Constantine was a “renewal, as it were, in his own person, of his father’s life and reign”. Constantinian coinage, sculpture, and oratory also show a new tendency for disdain towards the “barbarians” beyond the frontiers. He minted a coin issue after his victory over the Alemanni which depicts weeping and begging Alemannic tribesmen, “the Alemanni conquered” beneath the phrase “Romans’ rejoicing”. There was little sympathy for these enemies; as his panegyrist declared, “It is a stupid clemency that spares the conquered foe.”
Dresden bust of Maxentius
Following Galerius’ recognition of Constantine as caesar, Constantine’s portrait was brought to Rome, as was customary. Maxentius mocked the portrait’s subject as the son of a harlot and lamented his own powerlessness. Maxentius, envious of Constantine’s authority, seized the title of emperor on 28 October 306 AD. Galerius refused to recognize him but failed to unseat him. Galerius sent Severus against Maxentius, but during the campaign, Severus’ armies, previously under command of Maxentius’ father Maximian, defected, and Severus was seized and imprisoned. Maximian, brought out of retirement by his son’s rebellion, left for Gaul to confer with Constantine in late 307 AD. He offered to marry his daughter Fausta to Constantine and elevate him to Augustan rank. In return, 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 AD. Constantine now gave Maxentius his meagre support, offering Maxentius political recognition.
Constantine remained aloof from the Italian conflict, however. Over the spring and summer of 307 AD, he had left Gaul for Britain to avoid any involvement in the Italian turmoil; now, instead of giving Maxentius military aid, he sent his troops against Germanic tribes along the Rhine. In 308 AD, he raided the territory of the Bructeri, and made a bridge across the Rhine at Colonia Agrippinensium (Cologne). In 310 AD, 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 strengthened his power base in the West. Maximian returned to Rome in the winter of 307–308 AD, but soon fell out with his son. In early 308 AD, after a failed attempt to usurp Maxentius’ title, Maximian returned to Constantine’s court.
On 11 November 308 AD, Galerius called a general council at the military city of Carnuntum (Petronell-Carnuntum Austria) 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, one of Galerius’ old military companions, was appointed Augustus in the western regions. The new system did not last long: Constantine refused to accept the demotion and continued to style himself as Augustus on his coinage, even as other members of the Tetrarchy referred to him as a Caesar on theirs. Maximinus Daia was frustrated that he had been passed over for promotion while the newcomer Licinius had been raised to the office of Augustus and demanded that Galerius promote him. Galerius offered to call both Maximinus and Constantine “sons of the Augusti”, but neither accepted the new title. By the spring of 310 AD, Galerius was referring to both men as Augusti.
A gold multiple of “Unconquered Constantine” with Sol Invictus, struck in 313 AD. The use of Sol’s image stressed Constantine’s status as his father’s successor, appealed to the educated citizens of Gaul, and was considered less offensive than the traditional pagan pantheon to the Christians.
In 310 AD, a dispossessed Maximian rebelled against Constantine while Constantine was away campaigning against the Franks. Maximian had been sent south to Arles with a contingent of Constantine’s army, in preparation for any attacks by Maxentius in southern Gaul. He announced that Constantine was dead, and took up the imperial purple. In spite of a large donative pledge to any who would support him as emperor, most of Constantine’s army remained loyal to their emperor, and Maximian was soon compelled to leave. Constantine soon heard of the rebellion, abandoned his campaign against the Franks, and marched his army up the Rhine. At Cabillunum (Chalon-sur-Saône), he moved his troops onto waiting boats to row down the slow waters of the Saône to the quicker waters of the Rhone. He disembarked at Lugdunum (Lyon). Maximian fled to Massilia (Marseille), a town better able to withstand a long siege than Arles. It made little difference, however, as loyal citizens opened the rear gates to Constantine. Maximian was captured and reproved for his crimes. Constantine granted some clemency, but strongly encouraged his suicide. In July 310 AD, Maximian hanged himself.
In spite of the earlier rupture in their relations, Maxentius was eager to present himself as his father’s devoted son after his death. He began minting coins with his father’s deified image, proclaiming his desire to avenge Maximian’s death. Constantine initially presented the suicide as an unfortunate family tragedy. By 311 AD, however, he was spreading another version. According to this, after Constantine had pardoned him, Maximian planned to murder Constantine in his sleep. Fausta learned of the plot and warned Constantine, who put a eunuch in his own place in bed. Maximian was apprehended when he killed the eunuch and was offered suicide, which he accepted. Along with using propaganda, Constantine instituted a damnatio memoriae on Maximian, destroying all inscriptions referring to him and eliminating any public work bearing his image.
The death of Maximian required a shift in Constantine’s public image. He could no longer rely on his connection to the elder Emperor Maximian, and needed a new source of legitimacy. In a speech delivered in Gaul on 25 July 310 AD, the anonymous orator reveals a previously unknown dynastic connection to Claudius II, a 3rd-century emperor famed for defeating the Goths and restoring order to the empire. Breaking away from tetrarchic models, the speech emphasizes Constantine’s ancestral prerogative to rule, rather than principles of imperial equality. The new ideology expressed in the speech made Galerius and Maximian irrelevant to Constantine’s right to rule. Indeed, the orator emphasizes ancestry to the exclusion of all other factors: “No chance agreement of men, nor some unexpected consequence of favor, made you emperor,” the orator declares to Constantine.
The oration also moves away from the religious ideology of the Tetrarchy, with its focus on twin dynasties of Jupiter and Hercules. Instead, the orator proclaims that Constantine experienced a divine vision of Apollo and Victory granting him laurel wreaths of health and a long reign. In the likeness of Apollo Constantine recognized himself as the saving figure to whom would be granted “rule of the whole world”, as the poet Virgil had once foretold. The oration’s religious shift is paralleled by a similar shift in Constantine’s coinage. In his early reign, the coinage of Constantine advertised Mars as his patron. From 310 AD on, Mars was replaced by Sol Invictus, a god conventionally identified with Apollo. There is little reason to believe that either the dynastic connection or the divine vision are anything other than fiction, but their proclamation strengthened Constantine’s claims to legitimacy and increased his popularity among the citizens of Gaul.
See also: Civil wars of the Tetrarchy
War against Maxentius
Battles of Constantine I
By the middle of 310 AD, Galerius had become too ill to involve himself in imperial politics. His final act survives: a letter to provincials posted in Nicomedia on 30 April 311 AD, proclaiming an end to the persecutions, and the resumption of religious toleration. He died soon after the edict’s proclamation, destroying what little remained of the tetrarchy. Maximinus mobilized against Licinius, and seized Asia Minor. A hasty peace was signed on a boat in the middle of the Bosphorus. While Constantine toured Britain and Gaul, Maxentius prepared for war. He fortified northern Italy, and strengthened his support in the Christian community by allowing it to elect a new Bishop of Rome, Eusebius.
Maxentius’ rule was nevertheless insecure. His early support dissolved in the wake of heightened tax rates and depressed trade; riots broke out in Rome and Carthage; and Domitius Alexander was able to briefly usurp his authority in Africa. By 312 AD, he was a man barely tolerated, not one actively supported, even among Christian Italians. In the summer of 311 AD, Maxentius mobilized against Constantine while Licinius was occupied with affairs in the East. He declared war on Constantine, vowing to avenge his father’s “murder”. To prevent Maxentius from forming an alliance against him with Licinius, Constantine forged his own alliance with Licinius over the winter of 311–312 AD, and offered him his sister Constantia in marriage. Maximinus considered Constantine’s arrangement with Licinius an affront to his authority. In response, he sent ambassadors to Rome, offering political recognition to Maxentius in exchange for a military support. Maxentius accepted. According to Eusebius, inter-regional travel became impossible, and there was military buildup everywhere. There was “not a place where people were not expecting the onset of hostilities every day”.
Constantine’s advisers and generals cautioned against preemptive attack on Maxentius; even his soothsayers recommended against it, stating that the sacrifices had produced unfavourable omens. Constantine, with a spirit that left a deep impression on his followers, inspiring some to believe that he had some form of supernatural guidance, ignored all these cautions. Early in the spring of 312 AD, Constantine crossed the Cottian Alps with a quarter of his army, a force numbering about 40,000. The first town his army encountered was Segusium (Susa, Italy), a heavily fortified town that shut its gates to him. Constantine ordered his men to set fire to its gates and scale its walls. He took the town quickly. Constantine ordered his troops not to loot the town, and advanced with them into northern Italy.
At the approach to the west of the important city of Augusta Taurinorum (Turin, Italy), Constantine met a large force of heavily armed Maxentian cavalry. In the ensuing battle Constantine’s army encircled Maxentius’ cavalry, flanked them with his own cavalry, and dismounted them with blows from his soldiers’ iron-tipped clubs. Constantine’s armies emerged victorious. Turin refused to give refuge to Maxentius’ retreating forces, opening its gates to Constantine instead. Other cities of the north Italian plain sent Constantine embassies of congratulation for his victory. He moved on to Milan, where he was met with open gates and jubilant rejoicing. Constantine rested his army in Milan until mid-summer 312 AD, when he moved on to Brixia (Brescia).
Brescia’s army was easily dispersed, and Constantine quickly advanced to Verona, where a large Maxentian force was camped. Ruricius Pompeianus, general of the Veronese forces and Maxentius’ praetorian prefect, was in a strong defensive position, since the town was surrounded on three sides by the Adige. Constantine sent a small force north of the town in an attempt to cross the river unnoticed. Ruricius sent a large detachment to counter Constantine’s expeditionary force, but was defeated. Constantine’s forces successfully surrounded the town and laid siege. Ruricius gave Constantine the slip and returned with a larger force to oppose Constantine. Constantine refused to let up on the siege, and sent only a small force to oppose him. In the desperately fought encounter that followed, Ruricius was killed and his army destroyed. Verona surrendered soon afterwards, followed by Aquileia, Mutina (Modena), and Ravenna. The road to Rome was now wide open to Constantine.
The Milvian Bridge (Ponte Milvio) over the Tiber, north of Rome, where Constantine and Maxentius fought in the Battle of the Milvian Bridge
Maxentius prepared for the same type of war he had waged against Severus and Galerius: he sat in Rome and prepared for a siege. He still controlled Rome’s praetorian guards, was well-stocked with African grain, and was surrounded on all sides by the seemingly impregnable Aurelian Walls. He ordered all bridges across the Tiber cut, reportedly on the counsel of the gods, and left the rest of central Italy undefended; Constantine secured that region’s support without challenge. Constantine progressed slowly along the Via Flaminia, allowing the weakness of Maxentius to draw his regime further into turmoil. Maxentius’ support continued to weaken: at chariot races on 27 October, the crowd openly taunted Maxentius, shouting that Constantine was invincible. Maxentius, no longer certain that he would emerge from a siege victorious, built a temporary boat bridge across the Tiber in preparation for a field battle against Constantine. On 28 October 312 AD, the sixth anniversary of his reign, he approached the keepers of the Sibylline Books for guidance. The keepers prophesied that, on that very day, “the enemy of the Romans” would die. Maxentius advanced north to meet Constantine in battle.
Constantine adopts the Greek letters Chi Rho for Christ’s initials
Main article: Battle of the Milvian Bridge
Further information: Ponte Milvio
The Battle of the Milvian Bridge by Giulio Romano
Maxentius’ forces were still twice the size of Constantine’s, and he organized them in long lines facing the battle plain with their backs to the river. Constantine’s army arrived on the field bearing unfamiliar symbols on their standards and their shields. According to Lactantius, Constantine had a dream the night before the battle which advised him to “mark the heavenly sign of God on the shields of his soldiers… by means of a slanted letter X with the top of its head bent round, he marked Christ on their shields.” Eusebius describes a vision that Constantine had while marching at midday in which “he saw with his own eyes in the heavens and a trophy of the cross arising from the light of the sun, carrying the message, In Hoc Signo Vinces” (“with this sign, you shall win”). In Eusebius’s account, Constantine had a dream the following night in which Christ appeared with the same heavenly sign and told him to make an army standard in the form of the labarum. Eusebius is vague about when and where these events took place, but it enters his narrative before the war begins against Maxentius. He describes the sign as Chi (Χ) traversed by Rho (Ρ) to form ☧, representing the first two letters of the title Christos or Christ. A medallion was issued at Ticinum in 315 AD which shows Constantine wearing a helmet emblazoned with the Chi Rho, and coins issued at Siscia in 317/318 AD repeat the image. The figure was otherwise rare, however, and is uncommon in imperial iconography and propaganda before the 320s.
Constantine deployed his own forces along the whole length of Maxentius’ line. He ordered his cavalry to charge, and they broke Maxentius’ cavalry. He then sent his infantry against Maxentius’ infantry, pushing many into the Tiber where they were slaughtered and drowned. The battle was brief, and Maxentius’ troops were broken before the first charge. His horse guards and praetorians initially held their position, but they broke under the force of a Constantinian cavalry charge; they also broke ranks and fled to the river. Maxentius rode with them and attempted to cross the bridge of boats, but he was pushed into the Tiber and drowned by the mass of his fleeing soldiers.
Bronze head of Constantine from a colossal statue
Constantine entered Rome on 29 October 312 AD, and staged a grand adventus in the city which was met with jubilation. Maxentius’ body was fished out of the Tiber and decapitated, and his head was paraded through the streets for all to see. After the ceremonies, the disembodied head was sent to Carthage, and Carthage offered no further resistance. Unlike his predecessors, Constantine neglected to make the trip to the Capitoline Hill and perform customary sacrifices at the Temple of Jupiter. However, he did visit the Senatorial Curia Julia, and he promised to restore its ancestral privileges and give it a secure role in his reformed government; there would be no revenge against Maxentius’ supporters. In response, the Senate decreed him “title of the first name”, which meant that his name would be listed first in all official documents, and they acclaimed him as “the greatest Augustus”. He issued decrees returning property that was lost under Maxentius, recalling political exiles, and releasing Maxentius’ imprisoned opponents.
An extensive propaganda campaign followed, during which Maxentius’ image was purged from all public places. He was written up as a “tyrant” and set against an idealized image of Constantine the “liberator”. Eusebius is the best representative of this strand of Constantinian propaganda. Maxentius’ rescripts were declared invalid, and the honours were invalidated that he had granted to leaders of the Senate. Constantine also attempted to remove Maxentius’ influence on Rome’s urban landscape. All structures built by him were rededicated to Constantine, including the Temple of Romulus and the Basilica of Maxentius. At the focal point of the basilica, a stone statue was erected of Constantine holding the Christian labarum in its hand. Its inscription bore the message which the statue illustrated: By this sign, Constantine had freed Rome from the yoke of the tyrant.
Constantine also sought to upstage Maxentius’ achievements. For example, the Circus Maximus was redeveloped so that its seating capacity was 25 times larger than that of Maxentius’ racing complex on the Via Appia. Maxentius’ strongest military supporters were neutralized when he disbanded the Praetorian Guard and Imperial Horse Guard. The tombstones of the Imperial Horse Guard were ground up and used in a basilica on the Via Labicana, and their former base was redeveloped into the Lateran Basilica on 9 November 312 AD — barely two weeks after Constantine captured the city. The Legio II Parthica was removed from Albano Laziale, and the remainder of Maxentius’ armies were sent to do frontier duty on the Rhine.
Wars against Licinius
Coin of Licinius
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, officially granting full tolerance to Christianity and 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 and used only general terms to refer to the divine sphere — “Divinity” and “Supreme Divinity”, summa divinitas. The conference was cut short, however, when news reached Licinius that his rival Maximinus had crossed the Bosporus and invaded European 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, as Constantine suffered an assassination attempt at the hands of a character that Licinius wanted elevated to the rank of Caesar; Licinius, for his part, had Constantine’s statues in Emona destroyed. In either 314 or 316 AD, the two Augusti fought against one another at the Battle of Cibalae, with Constantine being victorious. They clashed again at the Battle of Mardia in 317, and agreed to a settlement in which Constantine’s sons Crispus and Constantine II, and Licinius’ son Licinianus were made caesars. After this arrangement, Constantine ruled the dioceses of Pannonia and Macedonia and took residence at Sirmium, whence he could wage war on the Goths and Sarmatians in 322, and on the Goths in 323, defeating and killing their leader Rausimod.
In the year 320, Licinius allegedly reneged on the religious freedom promised by the Edict of Milan in 313 and began to oppress Christians anew, generally without bloodshed, but resorting to confiscations and sacking of Christian office-holders. Although this characterization of Licinius as anti-Christian is somewhat doubtful, the fact is that he seems to have been far less open in his support of Christianity than Constantine. Therefore, Licinius was prone to see the Church as a force more loyal to Constantine than to the Imperial system in general, as the explanation offered by the Church historian Sozomen.
This dubious arrangement eventually 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 pagan faiths. Constantine and his Franks marched under the standard of the labarum, and both sides saw the battle in religious terms. Outnumbered, but fired by their zeal, Constantine’s army emerged victorious in the Battle of Adrianople. Licinius fled across the Bosphorus and appointed Martius Martinianus, the commander of his bodyguard, as Caesar, but Constantine next won the Battle of the Hellespont, and finally the Battle of Chrysopolis on 18 September 324. Licinius and Martinianus surrendered to Constantine at Nicomedia on the promise their lives would be spared: they were sent to live as private citizens in Thessalonica and Cappadocia respectively, but in 325 Constantine accused Licinius of plotting against him and had them both arrested and hanged; Licinius’s son (the son of Constantine’s half-sister) was also killed. Thus Constantine became the sole emperor of the Roman Empire.
Foundation of Constantinople