Julian defeated them completely, but allowed them to remain in Toxandria, not, as of old, as conquerors, but as foederati of the Romans.
For some time before 341 he worked as a lector (reader of the Scriptures), probably among his own countrymen in Constantinople, or among those attached as foederati to the Imperial armies in Asia Minor.
In the year 394 he served as a general of foederati (Gothic irregulars) under the emperor Theodosius in the campaign in which he crushed the usurper Eugenius.
The employment of barbarians as foederati, which became a common practice with the emperors in the 4th century, was both a symptom of disease in the body politic of the empire and a hastener of its impending ruin.
Three months later Stilicho himself and the chief ministers of his party were treacherously slain in pursuance of an order extracted from the timid and jealous Honorius; and in the disturbances which followed the wives and children of the barbarian foederati throughout Italy were slain.
At the great battle of Mauriac (the Catalaunian fields) in which Aetius checked the invasion of the Huns (451), there were present in the Roman army a number of Frankish foederati, and a later document, the Vita lupi, states that Merovech (Merovaeus) was their leader.
He persuaded the fugitive Visigoth king Athanaric to enter his service, and enlisted 40,000 of his former enemies as foederati, providing them with settlements in various parts of the realm.
Under the name of foederati they retained their original constitution and division into four cantons.
Vandals and foederati, or duly commissioned defenders of Sueai the Romans.