Invader of Gaul in 451 (6)

I believe the answer is:

attila

(Other definitions for attila that I've seen before include "Renowned Hun" , "The greatest Hun leader" , "Fifth century king of the Huns" , "The Scourge of God" , "First-century king of the Huns" .)

I've seen this clue in The New York Times.

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