In any case, eventually, Franks fought (451) in the Roman ranks at the great battle of Mauriac (the Catalaunian Fields), which arrested the progress of Attila into Gaul; and in the Vita Lupi, which, though undoubtedly of later date, is a recension of an earlier document, the name of Meroveus appears among the combatants.
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.
Then followed, in 451, that westward movement across the Rhine which was only arrested at last, with terrible slaughter, on the Catalaunian plains (according to common belief, in the neighbourhood of the modern Chalons, but more probably at a point some 50 m.
Attila, who knew the difficulty that he should have in feeding his immense army if his march was further delayed, turned again to the north-east, was persuaded by the venerable bishop Lupus to spare the city of Troyes, but halted near that place in the Catalaunian plains and offered battle to his pursuers Aetius and Theodoric. The battle which followed - certainly one of the decisive battles of the world - has been.
Accepted as allies, and supported by Roman prestige and by the active authority of the general Aetius, all these barbarians rallied round him and the Romans of Gaul, and ~fl 431 defeated the hordes of Attila, who had advanced as far as Orleans, at the great battle of the Catalaunian plains.