The Frankish invasion of Northern Gaul in 431 is in a sense a continuation of the
Frankish War of 428 and fits into the pattern of Frankish invasions in the first half of the fifth century. The cause of the war must be sought in the political situation of the Roman Empire at that time. For a large extent, it is the result of events at the beginning of the fifth century. The
Crossing of the Rhine and the
War of Radagaisus in
406, and the civil wars that followed had an enormous impact on the fighting power of the Roman army. The battles that were fought cost many lives. The army supplemented its shortages by withdrawing troops from the borders. For the
Limitanei, the border guards, this meant a great loss. Auxiliary troops from Franks, Burgundians and Alans largely took over their task. The loss of readiness of the Roman army became particularly evident on the border, where invasions from
Germania were not vigorously punished. As far as we know, the campaigns were not thorough enough to drive out the attackers. This was a break with the past, when attacks on Roman soil always were followed by retaliatory actions by the army. Peace negotiations only followed after a punitive expedition. Aëtius's actions in the previous Frankish war were also not thorough enough. Although the Romans inflicted heavy losses on the invaders, they did not pursue them across the Rhine for a punitive campaign. Aëtius's operation in northern Gaul seems to have been short-lived and, crucially, it took place on imperial territory. It is reasonable to assume that the situation in northern Gaul soon deteriorated again as a result. The Franks were indeed forced to make peace, but because the Romans lacked resources and manpower, they subsequently left the border guarding to them.
The Franks and Chlodio's participation It is unclear which Frankish tribe invaded northern Gaul in 431,
Hydatius and
Prosper provide no information on this. Of the Ripuarian Franks, who were settled east of the Rhine, we know that they attacked the city of
Trier in 410, 413, 420, 435 and 453/461. Of the Salian Franks, we only know that they settled in
Toxandria within the Roman Empire in 358 and only return to history shortly before the middle of the 5th century, by
Gregory of Tours, who at the end of the 6th century in his writings cited
Sulpicius Alexander and
Renatus Profuturus Frigeridus, and reports on King Chlodio. Chlodio may be the other main player in this war. He is the first Merovingian king whose existence is certain. Besides a brief mention in the
Historia Francorum by
Gregory of Tours, Chlodio is also mentioned in a
Panegyric by
Sidonius Apollinaris. He reports that around 448 Emperor
Majorianus (457–461) defended the city of
Tours against the Franks and that Aetius fought Chlodio in the open plains of
Artois. Although
Hydatius does not name a Frankish leader in his account of this event, historians suspect that Chlodio was already active in northern Gaul earlier. According to Gregory of Tours' account, Chlodio held power in the northernmost part of Gaul (Germania II) together with an area further to the northeast. == The campaign of Aetius ==