Which answer matches this clue: the 451 battle where the Roman general Aetius and his Visigothic allies halted Attila the Hun?

• A Battle of Adrianople
• B Battle of the Frigidus
• C Battle of the Milvian Bridge
• D Battle of the Catalaunian Plains ✓

The Catalaunian Plains was one of the last great Roman military operations in the West; Attila was forced to retreat from Gaul.