It was as governor of the province that Septimius Severus made his bid for the Roman Imperial throne in April 193 CE.

In 308 Emperor Diocletian chaired a historic meeting with his co-emperors Maximian and Galerius in Carnuntum, to solve the rising tensions within the Tetrarchy.

Diocletian and Maximian were both present on 11 November 308, to see Galerius appoint Licinius to be Augustus in place of Valerius Severus, who had died at the hands of Maxentius.

At Carnuntum people begged Diocletian to return to the throne, to resolve the conflicts that had arisen through Constantine the Great's rise to power and Maxentius' usurpation.

[1] Diocletian's reply: "If you could show the cabbage that I planted with my own hands to your emperor, he definitely wouldn't dare suggest that I replace the peace and happiness of this place with the storms of a never-satisfied greed.