The Roman forces in Britain were collapsing due to raiding Saxons (and others), so the legions took matters into their own hands by elevating one of their own, Constantine, to emperor. Constantine established his court at Arles (southern Gaul) in 407.
Under attack, the Western Empire suffered Germanic, Frank, Visigoth, and Burgundian attacks from all directions. With both northern and southern Gaul falling, the invaders would eventually close in on Constantine in Arles, but Constantine held them off long enough to win recognition from Honorius for his short-lived success.
Unfortunately, Constantine’s popularity would not last. Constantine’s Spanish commanders proclaimed their own emperor and Britain was too far from Arles to be controlled.
Constantine tried invading Italy, unsuccessfully, and fell out of favor with his magister militum, the Briton Gerontius, who then besieged him at Arles but fled when Honorius’ generals approached. Constantine had himself ordained priest and surrendered to Honorius' generals, but it did not save him. Honorius' new magister militum, Constantius, captured Constantine.
Honorius executed Constantine III in 411.
- Adkins, Leslie and Roy A. Adkins. Handbook to Life in Ancient Rome. OUP, New York, 1994
- Charles Freeman. Egypt, Greece and Rome: Civilizations of the Ancient Mediterranean. 2nd Edition. OUP, New York, 2004
- Hornblower, Simon and Antony Spawforth. The Oxford Classical Dictionary. 3rd Edition Revised. OUP, Oxford, 2003