Maxentius and Constantine
Clash of the Titans

    In 293 A.D., Diocletian started the tetrarchy. This reign of four rulers was a novel idea as it further divided up the workload of ruling a huge empire. The two Augusti, Diocletian and Maximian, each chose a Caesar. Diocletian chose Galerius and Maximianus chose Julius Constantius, the father of Constantine. This system worked just fine until the two senior Augusti abdicated (Maximian never actually wanted to abdicate, but only did so at the urging of Diocletian). The two Caesars became Augusti and needed to appoint their new Caesars. The new Caesars were Severus II and Maximinus Daia. The problem on the horizon was that Constantius had a son, Constantine, and Maximianus had a son, Maxentius. Both of these young men wanted advancement and fully expected, as the sons of emperors, to have power.

    Maxentius was the son of Maximian and he was born circa 279. He married Maximilla, the daughter of Galerius. Maxentius and Maximilla had a son named Romulus who died in 309.

    After the abdication of Diocletian and Maximian, Maxentius expected to become Caesar, but instead he was given the title of Princeps and semi-retired to Rome. In 306, the inhabitants of Rome rebelled against Galerius, who had issued a recent decree that meant they would lose their tax-free status. The citizens of Rome hailed Maxentius as Augustus. Galerius sent Severus II to reclaim Rome. However, the army of Severus defected over to Maxentius. Severus fled to Ravenna, but eventually surrendered in the hopes of a pardon. Maxentius executed him near Rome on 16 September 307.
    Maxentius asked his father, Maximian, to come out of retirement. Father and son repelled an attack by Galerius. They formed a brief alliance with Constantine. Constantine married Fausta, the daughter of Maximianus. Maximianus, however, tried to seize power in Rome in April of 308. His attempted coup failed and Maximian fled to Gaul and the protection of his son in law, Constantine. (Maximian later betrayed Constantine also and had to commit suicide in 310- Maxentius, ironically, deified his father and blustered about avenging his death). Maxentius was all alone and surrounded by enemies.
    After the death of Severus and defeat of Galerius, Maximianus and Galerius asked Diocletian to come out of retirement for a brief time. They met at Carnuntum, near Vienna. Licinius became Augustus in place of Severus and Constantine was officially recognized as Caesar. All agreed that Maxentius was a usurper and needed to be dealt with.
    In 308, Maxentius also lost the province of Africa when local troops there hailed Alexander of Carthage Augustus. This was a huge blow to Maxentius, because Africa was the breadbasket of Rome. This also made Alexander an ally of Constantine, at least as far as they both had a common enemy- Maxentius. There is a milestone in Africa that only mentions two Augusti- Constantine and Domitius Alexander. The army of Maxentius went to Carthage circa 311 and put Alexander to death. The Imperial mint of Carthage had probably already transferred to Ostia prior to the usurpation of Alexander, this would account for the crudeness of his coins- he did not have qualified mint personnel.
    On October 28, 312 A.D., Maxentius met Constantine outside of Rome. Maxentius could have stayed in heavily fortified Rome, but the citizens of Rome were restless and Maxentius was worried. He consulted the Sibylline Books, where he learned "on October 28 an enemy of the Romans will perish". His army left the city and crossed over to the right bank of the Tiber. In what can be viewed as the first crusade of Christianity against pagans (Rome was a Holy See), Constantine's forces routed the army of Maxentius at the battle of the Milvian Bridge. Ancient accounts vary- a pontoon bridge collapsed or a linchpin was pulled out early causing it to collapse, and Maxentius, along with many of his soldiers, drowned. Constantine’s soldiers recovered his body and paraded his head through Rome on a pike; and later it was sent to Africa.
    This is a pivotal battle in history and one of the great "what if" questions. These two men, who had similar backgrounds and were very close in age, should have been allies or even friends. They were even in-laws. They became enemies, instead. One has to wonder what might have happened if Maxentius had won that day. Constantine won though, and became undisputed ruler of the Western Empire.

This arch is in Rome between the Palatine Hill and the Colosseum, along the road taken by the triumphal processions, and in 315 A.D., the senate dedicated this monument to commemorate the victory of Constantine over Maxentius. The main inscription reads:
 
 
 

    To the Emperor Caesar Flavius Constantinus, the greatest, pious, and blessed Augustus: because he, inspired by the divine, and by the greatness of his mind, has delivered the state from the tyrant and all of his followers at the same time, with his army and just force of arms, the Senate and People of Rome have dedicated this arch, decorated with triumphs.

Further reading

Matts Cullhed, "Maxentius as Princeps." Opuscula romana 17 (1989) : 9-19.

________. Conservator Urbis Suae, Studies in the politics and Propaganda of the Emperor Maxentius. Stockholm: Åström Publishing, 1994.