General Magnentius deposes Roman Emperor Constans and proclaims himself Emperor.
Magnus Magnentius (c. 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 was acclaimed augustus. Magnentius quickly killed the unpopular emperor and gained control over most of the Western Empire. The Eastern emperor Constantius II, the brother of Constans, refused to acknowledge Magnentius' legitimacy and led a successful campaign against Magnentius in the Roman Civil war of 350-353. Ultimately, Magnentius' forces were scattered after the Battle of Mons Seleucus, and he committed suicide on 11 August 353.Much of Magnentius' short reign was concerned with asserting his legitimacy. Unlike Constans, Magnentius was unrelated to Constantine the Great, and so had no dynastic claim to the emperorship. Magnentius instead sought popular support by modeling himself as a liberator who had freed the Western Empire from the tyranny of Constans. Though attempted public and religious reform, his acts were quickly repealed by Constantius after his death. In light of the political instability of his reign, most modern and ancient historians consider him a usurper rather than an emperor.
Perhaps the most important consequence of Magnentius' revolt was the severe depletion of the Empire's military forces in civil war: The Battle of Mursa left so many Roman soldiers dead that, according to Zosimus, Constantius feared that Rome would no longer be able to effectively hold off barbarian invasion. Following his death, Constantius II became the sole emperor of the Roman Empire.