Europe 308: Council of Carnuntum

Maximian and Maxentius soon had a falling out and in April 308 Maximian took refuge with Constantine, encouraging Domitius Alexander in Africa to also break with Maxentius. That year Diocletian came out of retirement and, at Carnuntum in November, met with Galerius and Maximian in an attempt to restore stability to the empire. They agreed to appoint Licinius as a new Augustus, to confirm Constantine and Maximinus Daza as Caesars, and for Maximian to step down. For a moment an unprecedented eight emperors ruled the Roman world, but even after Diocletian and Maximian returned to retirement, a still daunting six remained.

Main Events

Apr 308 Exile of Maximian

In a public gathering in Rome in April 308, Maximian, angered by the execution of Severus, blamed his son Maxentius for the troubles they faced and attempted to relieve him of the rank of Augustus. The crowd and the army immediately sided with Maxentius, forcing Maximian to flee to Gaul and the court of his son-in-law Constantine.in wikipedia

308 Domitius Alexander

Following the exile of Maximian, Maxentius sent his own image to Carthage to demonstrate that he was now sole Augustus, but was rebuffed by the African legions, who had great respect for Maximian. When an angered Maxentius tried further measures to assert his authority in the region, the African legions revolted and proclaimed their vicarius Domitius Alexander as Augustus. Alexander—an elderly man who may have earlier served as Maximian’s praetorian prefect—quickly gained support across Africa and as far as Sardinia.in wikipedia

308 Constantine’s Bructeri Campaign

In 308, before the Council of Carnuntum, Constantine launched a campaign across the Rhine, making use of a bridge he had built near Colonia Agrippina (Cologne). This Roman raid devastated the Bructeri, a Frankish tribe who Constantine may have held responsible for the incursion of Ascaric and Merogais in 306/7.in wikipedia

11 Nov 308 Council of Carnuntum

In 308 Diocletian emerged from retirement to support Galerius and together the two met with Maximian at Carnuntum in November. Under the watch of Diocletian and Maximian, Galerius promoted his officer Licinius to become the new western Augustus, and confirmed Maximinus Daza and Constantine as Caesars. With the empire thus ‘stabilized’, Diocletian returned to his palace and cabbages at Salonae, while Maximian retired to Gaul.in wikipedia