Licinius - Conflict With Constantine I

Conflict With Constantine I

In 314, a civil war erupted between Licinius and Constantine, in which Constantine used the pretext that Licinius was harbouring Senecio, whom Constantine accused of plotting to overthrow him. Constantine prevailed at the Battle of Cibalae in Pannonia (October 8, 314). Although the situation was temporarily settled, with both men sharing the consulship in 315, it was but a lull in the storm. The next year a new war erupted, when Licinius named Valerius Valens co-emperor, only for Licinius to suffer a humiliating defeat on the plain of Mardia (also known as Campus Ardiensis) in Thrace. The emperors were reconciled after these two battles and Licinius had his co-emperor Valens killed.

Over the next ten years, the two imperial colleagues maintained an uneasy truce. Licinius kept himself busy with a campaign against the Sarmatians in 318, but temperatures rose again in 321 when Constantine pursued some Sarmatians, who had been ravaging some territory in his realm, across the Danube into what was technically Licinius’s territory. When he repeated this with another invasion, this time by the Goths who were pillaging Thrace, Licinius complained that Constantine had broken the treaty between them.

Constantine wasted no time going on the offensive. Licinius's fleet of 350 ships was defeated by Constantine I's fleet in 323. Then in 324, Constantine, tempted by the "advanced age and unpopular vices" of his colleague, again declared war against him, and, having defeated his army of 170,000 men at the Battle of Adrianople (July 3, 324), succeeded in shutting him up within the walls of Byzantium. The defeat of the superior fleet of Licinius in the Battle of the Hellespont by Crispus, Constantine’s eldest son and Caesar, compelled his withdrawal to Bithynia, where a last stand was made; the Battle of Chrysopolis, near Chalcedon (September 18), resulted in Licinius' final submission. While Licinius' co-emperor Sextus Martinianus was killed, Licinius himself was spared due to the pleas of his wife, Constantine's sister, and interned at Thessalonica. The next year, Constantine had him hanged, accusing him of conspiring to raise troops among the barbarians.