The Battle of the Catalaunian Plains (also called the "Battle of Châlons-sur-Marne" or "Battle of Châlons") was a battle in 451 AD. It took place in Châlons-sur-Marne, in northeast Gaul (nowadays France). Roman legions commanded by Flavius Aetius allied with Visigoth soldiers led by Theodoric I, to defeat the armies of Attila the Hun. 