Europe 350: Vetranio and Nepotian
After killing Constans in late January 350, Magnentius established his rule in the prefectures of Gaul and Italy. However, he was resisted in Illyricum, which proclaimed its own emperor, Vetranio, in March. Three months later Nepotian, one of Constantine I’s surviving nephews, rose against Magnentius in Rome, but was swiftly crushed.
Jan 350 Death of Constans▲
Learning of Magnentius’ usurpation in January 350, Constans fled for Spain, but was killed by Magnentius’ assassins at Helena, just north of the Pyrenees. With the death of Constans, the Praetorian Prefectures of Gaul and Italy declared for Magnentius.
1 Mar 350 Revolt of Vetranio▲
Learning of the death of Constans in January 350, the legions of Illyricum proclaimed their general Vetranio emperor at Mursa, in Pannonia. Old and unlettered, Vetranio at first protested the proclamation and asked Constantius II for aid, but by March had relented. Vetranio then signed a pact with his fellow usurper Magnentius and together they sent ambassadors to Constantius to request that he recognize them both as junior Augusti.
Apr–Sep 350 Shapur II’s Third Siege of Nisibis▲
Taking advantage of the turmoil following the overthrow of Constans in January 350, Shah Shapur II of Persia invaded Roman Mesopotamia and besieged Nisibis for the third time. After all the normal siege tactics failed, the Persians diverted the river Mygdonius to form a lake around the city and deployed siege engines on boats to break through the walls. When the Roman garrison repulsed even this attempt, the Persians gave up and withdrew, having suffered over 20,000 casualties over the four-month siege.
3–30 Jun 350 Nepotian▲
In early June 350 Nepotian, son of Constantine I’s half-sister Eutropia, was proclaimed emperor in Rome with the support of gladiators and brigands. Magnentius’ prefect Anicetus hastily gathered and armed a force of commoners to oppose him, but was easily defeated, prompting Magnentius to despatch his general Marcellinus to Italy. Marcellinus quickly regained control of Rome and by the end of the month Nepotian’s head was being paraded through the streets on a pike.