Late Roman Empire, Constantinian Dynasty (305-364), Tetrarchic Wars (306-324): Constantine-I/Maxentius’ Civil War [5/12], Licinius/Maximinus II Dias’ Civil War [6/12]

Constantine-I/Maxentius’ Civil War (312), [5/12]

In spring 312, Constantine swept over the Alps via the Mont Cenis Pass with a quarter of his army (about 40,000 men). At Segusium (=Susa), a heavily fortified town, he ordered his men to set fire to its gates and scale its walls. After taking the town he advanced towards the important city of Julia Augusta Taurinorum (=Turin), where he defeated a large force, including clibanarii (heavy cavalry). Turin opened its gates to him, as did Mediolanum. Here he rested his army until mid-summer, when he moved his army on to Brixia (=Brescia).

Brixia’s army was easily dispersed and Constantine quickly advanced to Verona, where a large enemy force, commanded by Maxentius’ praetorian prefect Ruricius Pompeianus, was encamped. Verona was in a strong defensive position, surrounded on three sides by the Adige River. A small force sent by Constantine to cross the river, defeated the detachment Ruricius sent against them and the town was put under siege.

Ruricius slipped away and returned with a larger force to oppose Constantine, who maintained the siege and sent part of his army to oppose him. In the battle that followed, Ruricius was killed and his army destroyed. Verona surrendered soon afterwards, followed by Aquileia, Mutina (=Modena) and Ravenna. Constantine was now master of northern Italy.

Maxentius had prepared Rome for siege, but changed his mind and decided to face the enemy in open battle. He led his army northward and crossed the Tiber by the Milvian Bridge, where the Via Cassia and Via Flaminia meet. Following the latter along the Tiber he found his path blocked by Constantine’s troops. Hemmed in between the hills and the river, Maxentius and thousands of his men perished in the Tiber. 

On 29 October, Constantine entered Rome, proclaiming his allegiance to the Cross, believing himself to have been borne on to victory by the favour of the God of the Christians, and the Senate conferred on him the title of senior augustus. In 313 he left for Milan to meet Licinius. During this meeting the two emperors made an agreement, known inaccurately as the ‘Edict of Milan’, was a letter to the governors of the Eastern provinces stating that all measures directed against the Christians were now defunct. Then, when the news reached Licinius that his rival Maximinus II Dias had crossed the Bosporus and invaded European territory, Licinius departed eastwards to deal with Maximinus

Licinius/Maximinus II Dias’ Civil War (313), [6/12]

Licinius engaged Maximinus on the Campus Serenus at Tzirallum (Thracia). The battle was a rout, and Maximinus fled back to Tarsus where he died a short time later, putting Licinius in possession of all the Eastern provinces.

Around this Constantine suggested handing over Italy to a new caesar, a certain Bassianus (d.316), who although married to another half-sister of Constantine, Anastasia, was also closely associated with Licinius. When it emerged that Bassianus’ brother Senecio, who was in service with Licinius, was behind a plot to assassinate Constantine, Licinius, justly or unjustly, was accused of instigating the plot. Constantine put Bassianus to death and demanded Senecio, who was in Licinius’ territory, should be handed over. Licinius refused and the relationship between the two augusti was broken.