10 de Junho de 451.

The Battle of Chalons, Flavius Aetius' victory over Attila the Hun. The Battle of Chalons, also called the Battle of the Catalaunian Fields or the Battle of the Catalun, took place in 451 between the allied forces and foederati led by the Roman general Aetius and the Visigothic king Theodorid on one side, and the Huns led by their king Attila and their allies. This battle was the last major military operation of the Western Roman Empire.

Both armies consisted of combatants from many peoples. Jordanes lists Aetius' allies as including (besides the Visigoths) both the Salic and Riparian Franks, Sarmatians, Armoricans, Liticians, Burgundians, Saxons, Olibrones (whom he describes as "once Roman soldiers and now the flower of the allied forces"), and other Celtic or German tribes (Getica 36.191). Jordanes' list for Attila's allies includes the Gepids under their king Ardaric, as well as an Ostrogothic army led by the brothers Valamir, Theodemir (the father of the later Ostrogothic king Theodoric the Great) and Vidimer, scions of the Amali (Getica 38.199). Sidonius offers a more extensive list of allies: Rugians, Gepids, Gelonians, Burgundians, Scirans, Bellonotians, Neurians, Bastarnae, Thuringians, Bructeri, and Franks living along the Neckar River (Carmina 7.321-325). E.A. Thompson expresses his suspicions about some of these names:
The Bastarnae, Bructeri, Geloni and Neuri had disappeared hundreds of years before the times of the Huns, while the Bellonoti had never existed at all: presumably the learned poet was thinking of the Balloniti, a people invented by Valerius Flaccus nearly four centuries earlier.5
Thompson, however, believes that the presence of Burgundians on the Hunnic side is credible, noting that a group is documented as remaining east of the Rhine; likewise, he believes that the other peoples Sidonius alone mentions—the Rugians, Scirans and Thuringians—were likely participants in this battle.

However, the number of participants for either side—or in total—is entirely speculative. Jordanes' offers the number of dead from this battle is 165,000, excluding the casualties of the Franko-Gepid skirmish previous to the main battle. Hydatius, a historian who lived at the time of Attila's invasion, reports the number of 300,000 dead. No primary souce offers an estimate for the number of participants. The figures of both Jordanes and Hydatius are implausibly high; Thompson remarks in a footnote,"I doubt that Attila could have fed an army of even 30,000 men."5 As a reference, in the early 3rd century, the Roman Empire maintained 30 legions with just under 5200 actual men each; if we follow the general assumption that the number of auxiallaries matched the number of legionaries, then add the Praetorian Guard as 5,000 strong, and 6 Urban Cohorts, we find that the Empire at its height fielded a total 323,000 all told across its territories.6

A better sense of the size of the combatants may be found in the study of the Notitia Dignitatum by A.H.M. Jones.7 This document is a list of officials and military units that Jones believes was last updated in the first decades of the 5th century. He identified 58 various regular units, and 33 limitani serving either in the Gallic provinces or on the frontiers; the total of these units, based on his analysis, is 34,000 for the regular units and 11,500 for the limitani, or just under 46,000 all told. While the Roman forces in Gaul had become much smaller by this time, if we accept this number as the total for all of the forces fighting with Theodorid and Aetius, we should not be too far off. Assuming that the Romano-Gothic and Hunnic forces were about equal in size, then in total the battle involved just under 100,000 combatants, excluding the inevitable servants and camp followers who almost always escape mention.

Wikipedia.