Which people were defeated by Theodoric and Aetius at the Catalaunian Plains in 451 A.D.?

The correct answer is that the Huns were the people defeated by Theodoric and Aetius at the Catalaunian Plains in 451 A.D. This battle, also known as the Battle of Chalons, was one of the critical confrontations during the decline of the Western Roman Empire. The alliance of the Roman general Aetius and the Visigothic king Theodoric was pivotal in halting the advance of Attila the Hun, who was leading a massive invasion into Gaul.

The significance of this victory lies in its demonstration of unity among the Romans and various German tribes, which was uncommon during this fragmented period of history. The defeat of the Huns marked a turning point in their invasions of the Roman territories, showcasing the effectiveness of combined military strategies among the allies.

In contrast, the Visigoths, Ostrogoths, and Franks were not the parties involved in this conflict against Aetius and Theodoric at this specific battle; rather, the Visigoths were allied forces during this confrontation against the Huns. The Ostrogoths and Franks played different roles in the broader historical context of the time and were not present as opposing forces in this specific battle.