At that time, God's Whip - Attila was trapped by the Marne River, and Aetius was estimated to still want to let him go.
Should Duncan pursue? Or not?
Aetius letting God's Whip escape might have many considerations, like using the Huns to balance the Barbarian Race, their private friendship, because the Western Goths had shown exceptional courage in the war, if they killed God's Whip, they would surely shock Europe and become uncontrollable, etc.
It's even possible that he wanted to nourish bandits to bolster his own strength, with God's Whip alive being more advantageous to him, etc.
But these are all reasons for Protector of the Realm - Aetius.
Duncan doesn't need to consider these.
All he needs to consider is one point, if God's Whip - Attila is greatly defeated, should he seize the opportunity to kill the opponent!
The Eighteen Lords launched a campaign against Dong Zhuo.