Magnentius was a military commander in Gaul who rebelled against the Roman emperor Constantius II, removing and killing his junior colleague Constans, in the west. He appears to have had widescale support in Britain, Gaul and Hispania because he proved to be far more tolerant towards both Catholic Christians and Pagans. His rival Constantius subscribed to the heretical doctrine of Arianism. He failed in his attempts to invade Constantius’s territory, and was finally defeated at the Battle of Mons Seleucus in France in 353 CE. Harsh and repressive counter measures were taken against his supporters.