All miscalculated

Beihuan, it is not necessary to have cavalry!
As Adagio Swift's voice fell, everyone was stunned.
"Your Highness, do you mean that Beihuan is attacking with infantry?"
Feng Yu frowned slightly, "But the speed of the infantry shouldn't be that fast, right?"
At most, infantrymen can run thirty or forty miles a day, and that is based on the premise of just marching.
The Northern Huan army was able to move to the vicinity of Suining Guard so quickly, it couldn't be infantry, right?
"Your...