Aureolus was a Roman military commander during the reign of Emperor Gallienus before he attempted to usurp the Roman Empire. After turning against Gallienus, Aureolus was killed during the political turmoil that surrounded the Emperor's assassination in a conspiracy orchestrated by his senior officers. Aureolus is known as one of the Thirty Tyrants and is referenced in ancient sources including the Historia Augusta, Zonaras' epitome and Zosimus' Historia Nova.
Biography
Early life
Aureolus was born in the Roman province of Dacia, north of the Danube, and prior to his military career served as a herdsman as well as Master of the Imperial Horses ('Phronistes'). both of which were common praenomina within the Acilia gens. Although some historians such as John Platts, William A'Beckett and Angelo Paredi have thought the 'M' to stand for a second nomen Manlius.
It is unclear whether Aurelous came to the attention of the Emperor Gallienus after enlisting in the army, or during his service as a groom. Gallienus was known to promote talent from outside the establishment, and Aureolus was one of the New Men who replaced senators in positions of high command in the army in the course of his reign.
Career
As a former Imperial Horsemaster, Aureolus developed a self-contained cavalry force to increase the effectiveness of the comitatus as a highly mobile field army under the Emperor's direct control. Aureolus was the first commander of this force under the Emperor, and was based at Mediolanum (Milan).
Aureolus' cavalry was principally responsible for the defeat of the usurper Ingenuus at the Battle of Mursa (Osijek) in 258. In 261, he commanded the force which defeated the army of the usurpers Macrianus Major and Macrianus Minor in battle somewhere in the central Balkans. The army of the Macriani, which first supported usurper Ingenuus and then Regalianus, included inmates from garrisons in Danubian provinces and was estimated to be at least 30,000 strong.
The success of Aureolus in suppressing the Macriani is thought by some historians to have undermined the achievements of Gallienus. Other historians suggest that at this time Gallienus was attempting to crush the Gallic usurper Postumus, who murdered Gallienus's son Caesar Saloninus, and clear the Juthungi out of the Alpine province of Raetia where they posed a direct threat to Italy and Rome.
Rebellion
After the Macriani were defeated and the Danubian garrison forces who had supported them were pacified, Aureolus and the Emperor united to defeat Postumus and his Gallic Empire. It may have been as a result of this campaign that the province of Raetia was recovered from the Gallic Empire and Postumus's inscription on the Augsburg Altar was erased. However, Postumus managed to evade complete defeat, which some historians blame on the alleged 'carelessness' of Aureolus. Other historians have suggested that Aureolus deliberately allowed the Gallic usurper to evade destruction to see Gallienus displaced as Emperor.
Zosimus