Flavius Constantius began as a soldier in the roman army and attracted the attention of the emperor Honorius after several successful defensive campaigns on behalf of the Western Empire.
He deterred several attacks by barbarian forces and also ended the revolt of Constantine III who was attempting to take over the throne. Due to Honorius’ weak disposition, Constantius was able to manipulate him and influence his decisions. In 417 Constantius married the sister of Honorius and was then given the title of co-emperor and ruled over the west.
The emperor of the east, Theodosius II, refused to acknowledge Constantius’ rule but while preparing a campaign against him Constantius died suddenly.