Answer:
The veterans scoffed because the soldiers at the front started to flee before they even fought.
Step-by-step explanation:
This question is about "The Red Badge of Courage".
The veterans of the troop had started to make fun of the younger soldiers who were in front because they started to flee in despair at the first sign of gunshots and confusion. They hadn't even started fighting and Ios, it somehow seemed funny to veterans who knew that what was going on would continue to happen so many times that the young soldiers couldn't even imagine it.