The year was 451, and the battle of Chalons (also known as Catalaunian Fields and Campus Martius) was fought between a coalition of Roman legionnaires, Germanic Visigoths, and Gauls against the Huns. Flavius Aetius was the Roman commanding general, and he led his forces to defeat Attila, king of the Huns and commander of the Hun armies. The loss caused Attila to withdraw and skirmish into Italy, but again (this time through diplomacy and concessions) he withdrew in 452, returning into what is now modern Hungary. Attila died in 453, and the Hun menace to Europe had ended.
Aetius had been the declining (and fragmented) Western Roman Empire’s best chance to restructure itself. He had fought in Gaul and throughout Italy and Europe for decades, sometimes even with support from the Huns before Attila began his quest for empire. A master strategist, tactician, diplomat, and warrior, he effectively stemmed the collapse of the Western Roman Empire for another 25 years. In all probability, he may have been able to turn things around for a longer period of time.
This was not to be, as he was assassinated by none other than the Emperor Valentinian III and his henchman Heraclius on 22 September 454.
The emperor killed the very man who had protected and assured his throne, and worse: now there was no true strategist to take the reins of military command. The last great Roman general was no more, and the Western Roman Empire continued to decline and fragment. Odoacer, a half-Hunnish barbarian general rallied forces to mutiny against their (and his) previous commander, Orestes, the Roman Senior military general, in the Battle of Pavia on August 23, 476. Orestes was captured and killed. Less than two weeks later, on or about September 4, 476, Romulus Augustulus, the last Roman emperor and the son of Orestes was deposed by Odoacer…..more here