Conference of Carnuntum

The Conference of Carnuntum (Latin: Carnuntum) was a military conference held on November 11, 308, in the city of Carnuntum (present-day Petronell-Carnuntum, Austria), which at the time was located in the province of Pannonia Prima. It was convened by the Augustus (senior Roman emperor) in the East Galerius (r. 293–311) as a way to settle the dispute over the title of Augustus in the West, and consequently, to cease the ongoing conflicts since the previous year when he, and before that Severus II (r. 305–307), invaded the Italy of Maxentius (r. 306–312) and Maximian (r. 286–308; 310). Present at the conference were Diocletian (r. 284–305), who had been retired since 305, and his former colleague, Maximian.

According to deliberations at the meeting, Maximian was to retire permanently from his imperial position; Licinius (r. 308–324), a former general of Galerius, was raised as the western Augustus and was to deal with Maxentius, who had been treated as an usurper; and Constantine (r. 306–337) was relegated, for the second time, to western Caesar. These decisions, however, did not please most of them: Constantine questioned his demotion and persisted in using the style of Augustus; Maximinus (r. 305–313) demanded promotion from Galerius; Maximian would not be satisfied with his demotion and would attempt one last conspiracy, in 310, at the court of Constantine in Arles, while Licinius would do nothing in the following years to stop Maxentius.