The Whole North Into Gaul

[Flavivs Aetivs]

You raise some excellent points, but as far as I can tell, it seems the Romans had not taken the brunt of the battle. Tonatius Ferreolus had supplied Aetius and his Allies for the campaign (Sid. Apol. Epist. 7.9) and the Romans had Attila pinned in his camp. It was simply a matter of surrounding Attila to destroy him at that point.

However, Ian Hughes suggests that Aetius still thought he could rely on the Huns for support in the future, and therefore let them go. I agree with this, but there were probably factors in play that haven't been passed down to us.

We also know that the Romans still had the capability to outright destroy some of the smaller tribes - the Burgundians were destroyed by Aetius' and Litorius' Hunnic retainers in 436 and 437. The Salian franks were driven back across the Rhine and that border was secured by 446.The Bacaudae in Armorica, Raetia, the Alps, and Spain were quelled several times as well.