Battle of the Catalaunian Plains

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. 
Attila's armies consisted mainly of horsemen. The battle ended as a stalemate - and thus a victory for the West, the Huns having suffered too many losses to continue their attack. The battle of the Catalaunian Plains crushed Attila's dreams of invading the Roman empire, and ultimately was the end of his empire in Europe. But the battle also weakened the already fragile Western Roman Empire, which collapsed 25 years later, in 476.