Europe 407: Revolt of Constantine III
The invasion of Gaul by the Vandals, Alans, and Suebi at the end of 406 caused a crisis in Roman Britain. In early 407 the British legions proclaimed the military veteran Constantine III as emperor and, stripping the island of most of its garrisons, crossed the Channel to confront the invaders.
31 Dec 406–? ?? 407 Sack of Belgica and Germania▲
After crossing the Rhine, the Vandals, Alans, and Suebi rampaged across northern Gaul, sacking Mogontiacum (Mainz), Durocortorum (Reims), Samarobriva (Amiens), Argentoratum (Strasbourg), and other cities in the provinces of Belgica and Germania. Their exact path is uncertain, but it is possible that they moved first towards the northern coast then back towards the Rhine upon the arrival of Constantine III and the British army. On their way south, they attacked the regional center of Augusta Treverorum (Trier) but were successfully repelled.
407 Pannonian Vandals▲
Learning of the crossing of the Rhine in early 407, but as yet unaware of the size or composition of the forces involved, the Western generalissimo Stilicho dispatched a body of Vandal foederati that had long been serving in Pannonia to help check the invaders. Unfortunately, the invaders also included large numbers of Vandals and, upon arriving in Gaul, the foederati were met with hostile suspicion by the local Romans. Denied food and supplies by Gaul’s cities, the Pannonian Vandals soon decided to cut ties with Rome and join the invaders instead.
Feb 407 Revolt of Constantine III▲
In early 407 the rebel Roman legions in Britain killed their usurper Gratian—who had proved unwilling to go on the offensive against the Vandals, Alans, and Suebi ravaging Gaul—and proclaimed Flavius Claudius Constantinus, a veteran soldier, as emperor in his place. Constantinus, or Constantine III as he would be known, was a popular choice among the troops, at least in part because his namesake, Constantine the Great, had also risen to power in Britain. The new emperor immediately gathered most of Britain’s remaining forces—possibly stripping the defenses of Hadrian’s Wall for the last time—and began making preparations to cross onto the continent.
407 Saxon raids on Gaul▲
Exploiting the chaos caused by the Rhine crossing of the Vandals, Alans, and Suebi, the Saxons mounted a raid on the Gallic coast in early 407. They seem to have achieved little, and were probably defeated by the Roman British usurper Constantine III soon after he landed in Gaul.
407 Illyricum Campaign▲
By 404 relations had broken down between the Western generalissimo Stilicho and the Eastern court of Arcadius. Perhaps taking advantage of instability in the East follow the death of Augusta Eudoxia in October of that year, Stilicho promoted Alaric to magister militum and, soon after the defeat of Radagaisus in late 406, encouraged him to invade the Eastern prefecture of Illyricum. Alaric quickly occupied Epirus, where he waited for Stilicho to join him until mid 407, when Stilicho abandoned the endeavor upon learning of Constantine III’s invasion of Gaul.
407 Constantine III’s invasion of Gaul▲
After appointing the Briton Justinianus and the Frank Nebiogast as his magistri militum, Constantine III crossed from Britain into Gaul with what was probably Britain’s entire field army in the spring of 407. Landing at Bononia (Boulogne-sur-Mer), the new emperor defeated some enemies (likely Saxons) and swiftly won the allegiance of both local Western Roman forces and the Franks. By late summer he had reached Lugdunum (Lyon), where he minted coins declaring himself “Restorer of the Republic” and co-augustus with Honorius, Arcadius, and Theodosius II.