The Battle of the Catalaunian Plains (or Fields), also called the Battle of the Campus Mauriacus, Battle of Chlons, Battle of Troyes or the Battle of Maurica, took place on June 20, 451 AD, between a coalition led by the Roman general Flavius Aetius and by the Visigothic king Theodoric I against the Huns and their vassals commanded by their king Attila. It proved one of the last major military operations of the Western Roman Empire, although Germanic foederati composed the majority of the coalition army. Whether the battle was strategically conclusive remains disputed: the Romans possibly stopped the Huns' attempt to establish vassals in Roman Gaul. However, the Huns successfully looted and pillaged much of Gaul and crippled the military capacity of the Romans and Visigoths. Attila died only two years later in 453, and after the Battle of Nedao (454) a coalition of the Huns' Germanic vassals dismantled his Hunnic Empire.

The Sack of Aquileia occurred in 452, and was carried out by the Huns under the leadership of Attila.