In the summer of 311 AD, Maxentius mobilized against Constantine to avenge his father’s supposed 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.
To ensure this alliance Constantine offered his sister Constantia in marriage to Licinius. Maximin considered Constantine’s arrangement with Licinius an insult to his authority. Military buildup sprung up everywhere, thus making inter-regional travel became impossible.
Constantine’s advisers, generals, and even his soothsayers cautioned against anticipatory attack on Maxentius. Constantine ignored all these concerns and, in early spring of 312 AD, he crossed the Cottian Alps with a force numbering about 40,000.
Segusium, a heavily fortified town, was the first Constantine’s army encountered. When the town shut its gates on him, Constantine ordered his men to burn the town. Needless to say, Segusium was quickly taken. Constantine ordered his troops not to loot the town, and advanced with them into northern Italy.
Advancing on western Augusta Taurinorum, a quite important city, Constantine met a large force of heavily armed Maxentian cavalry. In the following battle Constantine’s army surrounded Maxentius’s cavalry, flanked them with his own cavalry, and dismounted them with blows from his soldiers’ iron-tipped clubs. Victory fell upon the armies of Constantine.
Turin was just one of the towns that refused refuge for Maxentius and his retreating forces. While on his way to Milan, cities of the north Italian plain sent Constantine embassies of congratulation for his victory.
Upon arrival in Milan, Constantine was met with open gates and triumphant rejoicing, almost as if he had freed Milan himself. Constantine rested his army there until mid-summer 312 AD, when he moved on to Brixia.
Brixia’s army was easily broken up as Constantine hurriedly moved on to Verona, and a large Maxentian force. Maxentius’s Praefectus Praetorio, Ruricius Pompeianus, was in a strong defensive position with the town was surrounded on three sides by the Adige River.
Attempting to surround the town, Constantine sent a small force north and defeated a large detachment of forces sent by Ruricius. Constantine’s forces were able to surround the town and lay siege upon it.
Ruricius escaped only to return with more forces. Constantine refused to let up on the siege, again sending only a small force against Ruricius. In the encounter that followed, Ruricius was killed, his army annihilated, and Verona surrendered soon after. The road to Rome was open for Constantine.
Maxentius sat in Rome and prepared the city for a siege. Maxentius still controlled Rome’s Praetoriani, had plenty of African grain, and was surrounded by the Aurelian Walls which seemed almost impenetrable. Maxentius left the rest of central Italy undefended, allowing Constantine to secure the support of these people without any effort.
Constantine slowly advanced along the Via Flaminia, allowing Maxentius to further weaken. No longer certain of victory from a siege, Maxentius built a temporary boat bridge across the Tiber in case escape was needed.
On 28 October 312 AD, Maxentius advanced north with forces twice the size of Constantine’s to meet in battle. Constantine’s army arrived at the field bearing unfamiliar symbols on its standards and soldiers’ shields.
Constantine supposedly had a dream the night before the battle, wherein he was advised “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.”
Another version states while marching at midday, Constantine “saw with his own eyes in the heavens a trophy of the cross arising from the light of the sun, carrying the message, In Hoc Signo Vinces.
Constantine was said to have a dream the following night, in which Christ appeared with the same heavenly sign, and told him to make the labarum for his army in that form. The sign was Chi (Χ) traversed by Rho (Ρ) to give the Chi Rho: ☧, a symbol representing the first two letters of the Greek spelling of the word Christos or Christ.
Constantine deployed his own forces along the whole length of Maxentius’s line. Maxentius’s horse guards and Praetorians initially held their position, but broke under the force of a Constantinian cavalry charge. The infantry of Constantine pushed forward causing Maxentius’s soldiers to break ranks and flee.
Many of those that fled headed to the Tiber, where they were slaughtered. Maxentius rode with them, and attempted to cross the bridge of boats, but he was pushed by the mass of his fleeing soldiers into the Tiber, and drowned. This massive victory for Constantine is recalled as the Battle of the Milvian Bridge.
Constantine entered Rome on 29 October, where he staged a grand adventus, and was met with popular jubilation. Maxentius’s severed head was sent to Carthage causing no further resistance. Unlike previous victors, Constantine did not travel to Capitoline Hill and make sacrifices at the Temple of Jupiter Optimus Maximus.
He instead chose to honor the Senatorial Curia with a visit. Here Constantine promised to restore its ancestral privileges and give it a secure role in his reformed government.
There would be no revenge against supporters of Maxentius. Property lost under Maxentius was returned, political exiles were recalled, and imprisoned political opponents were released. Because of his acts of kindness the Senate acclaimed Constantine as the “Greatest Augustus“.
Maxentius’s image was systematically purged from all public places, and the honors he had granted to leaders of the Senate were invalidated. All structures built by Maxentius were re-dedicated to Constantine, including the Temple of Romulus and the Basilica of Maxentius.
A stone statue of Constantine holding the Christian labarum in its hand was erected at the basilica. The inscription bore the message: By this sign Constantine had freed Rome from the yoke of the tyrant. Constantine was shown in an idealized image of the “liberator”.
Maxentius’s strongest supporters in the military were neutralized when the Praetoriani and Equites Singulares Augusti were disbanded. On 9 November 312 AD, barely two weeks after Constantine captured the city, the former base of the Imperial Horseguard was chosen for redevelopment into the Lateran Basilica. The Legio II Parthica was removed from Alba and the remainders of Maxentius’s armies were sent to do frontier duty on the Rhine.
Constantine gradually consolidated his military superiority over his rivals in the crumbling Tetrarchy in the following years. In 313 AD, he met Licinius in Milan to secure their alliance and agreed on the 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 of “Divinity” and “Supreme Divinity”, Summa Divinitas.
The conference was cut short when news reached Licinius that rival Maximin had crossed the Bosporus and invaded European territory. Licinius departed and defeated Maximin, gaining control over the entire eastern half of the Roman Empire. Relations between Constantine and Licinius, the two remaining emperors, deteriorated when a compatriot of Licinius attempted to assassinate Constantine.
In either 314 or 316 AD, the two Augusti fought against one another at the Battle of Cibalae, with Constantine again victorious despite being outnumbered. They clashed again at the Battle of Mardia in 317 AD with both sides inflicting heavy injuries on each other.
A settlement was agreed to in which Constantine’s sons Crispus and Constantine II, and Licinius’ son Licinianus were all made Caesars. After this arrangement, Constantine ruled the dioceses of Pannonia and Macedonia. From his residence in Sirmium, he waged war on the Sarmatians in 322 AD and on the Goths in 323 AD.
In the year 320 AD, Licinius allegedly reneged on the religious freedom promised by the Edict of Milan and began to oppress Christians once more seeing the Church as a force more loyal to Constantine than to the Imperial system in general. This eventually became a challenge to Constantine in the West causing 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 fervor, Constantine’s army was victorious in the Battle of Adrianople, again at the Battle of the Hellespont, and finally the Battle of Chrysopolis on 18 September 324 AD. Licinius and Martinianus surrendered to Constantine at Nicomedia on the promise their lives would be spared.
Licinius was sent to live as a private citizen in Thessalonica while Martinianus was sent to Cappadocia to do the same. In 325 AD Constantine accused Licinius of plotting against him and had both Licinius and Martinianus arrested and hanged, while Licinius’s son was also killed.
This left Constantine as the sole emperor of the Roman Empire. In the West, Christianity and Latin-speaking were the standard. The defeat of Licinius came to represent the defeat of pagan and Greek-speaking political activity in the East. This led to proposal for a new Eastern capital to be the center of learning, prosperity, and cultural preservation for the whole of the Eastern Roman Empire.
Many locations were proposed for this alternative capital. With Constantine saying “Serdica is my Rome” many thought Serdica to be the spot. Having already been extensively rebuilt on Roman patterns of urbanism Constantine decided to work on the Greek city of Byzantium.
The century prior Byzantium had already acknowledged for its strategic importance by other emperors. Thus the city was founded in 324 AD, dedicated on 11 May 330 AD, and renamed Constantinopolis aka Constantine’s City.
To honor the event special commemorative coins were issued in 330 AD. The new city was protected by the relics of the True Cross, the Rod of Moses and other holy relics. The figures of old gods were restored or incorporated into the structure of Christian symbolism. Constantine built the Church of the Holy Apostles on the site of the Temple of Aphrodite. The capital would often be called Nova Roma Constantinopolitana, the “New Rome of Constantinople”.
The story of Constantine is not over. The conclusion is still to come. Untill then, Don’t Stop Rome-ing!