The Battle of Mons Seleucus was fought in 353 between the forces of the Roman emperor

Constantius II Constantius II (Latin: ''Flavius Julius Constantius''; grc-gre, Κωνστάντιος; 7 August 317 – 3 November 361) was Roman emperor from 337 to 361. His reign saw constant warfare on the borders against the Sasanian Empire and Germani ...

and the forces of the usurper

Magnentius Magnus Magnentius ( 303 – 11 August 353) was a Roman general and usurper against Constantius II from 350 to 353. Of Germanic descent, Magnentius served with distinction in Gaul under the Western emperor Constans. On 18 January 350 Magnentius ...

. Constantius' forces were victorious, and Magnentius later committed suicide.

Background

Following his defeat at

Mursa Osijek () is the fourth-largest city in Croatia, with a population of 96,848 in 2021. It is the largest city and the economic and cultural centre of the eastern Croatian region of Slavonia, as well as the administrative centre of Osijek-Baranja ...

, Magnentius fled to

Aquileia Aquileia / / / / ;Bilingual name of ''Aquileja – Oglej'' in: vec, Aquiłeja / ; Slovenian: ''Oglej''), group=pron is an ancient Roman city in Italy, at the head of the Adriatic at the edge of the lagoons, about from the sea, on the river N ...

. This campaign included summoning all those loyal to him to support him in Aquileia.

Decentius Magnus Decentius (died 18 August 353) was ''caesar'' of the Western Roman Empire from 350 to 353, under his brother Magnentius. History Nothing is known of Decentius prior to 350. Magnentius usurped power from Constans on 18 January 350, and e ...

, brother of Magnentius and newly made Caesar, was engaged with an incursion of

Alemanni The Alemanni or Alamanni, were a confederation of Germanic tribes * * * on the Upper Rhine River. First mentioned by Cassius Dio in the context of the campaign of Caracalla of 213, the Alemanni captured the in 260, and later expanded into pres ...

, and was unable to lend his army to support Magnentius. Constantius spent his time recruiting troops and retaking towns occupied by Magnentius. In the summer of 352, Constantius moved into Italy, only to find that Magnentius had chosen not to defend the peninsula.

Battle

The armies met at Mons Seleucus, in what is now

La Bâtie-Montsaléon La Bâtie-Montsaléon (; oc, La Bastia Montsaleon) is a commune in the Hautes-Alpes department in southeastern France. It is notable for being the location of the Battle of Mons Seleucus in 353, when Constantius II defeated the usurper Magnenti ...

in Hautes-Alpes, south-eastern France. Constantius was again victorious and Magnentius took his own life on 10 August 353. Following his conclusive battle, Constantius wintered his troops at Arles.

Aftermath

Constantius, now undisputed Emperor of the Roman Empire, appointed Julian ''Caesar'' over the western half of the Empire in 355/6, and instigated a campaign to persecute those who had supported Magnentius. According to

Ammianus Marcellinus Ammianus Marcellinus (occasionally Anglicisation, anglicised as Ammian) (born , died 400) was a Roman soldier and historian who wrote the penultimate major historical account surviving from Ancient history, antiquity (preceding Procopius). His w ...

, Constantius had become more "cruel, violent, and suspicious with age", and his ''notarii'' and bodyguards needed no pretext beyond mere suspicion to inflict punishment.

Notes

References

Sources

* * * * 353 Mons Seleucus 353 Mons Seleucus 353 350s in the Roman Empire

Mons Seleucus Mons (; German and nl, Bergen, ; Walloon and pcd, Mont) is a city and municipality of Wallonia, and the capital of the province of Hainaut, Belgium. Mons was made into a fortified city by Count Baldwin IV of Hainaut in the 12th century. T ...

Hautes-Alpes

Constantius II {{AncientRome-battle-stub