What kind of a raid did Ishmael and the other boy soldiers do? What was so big on that impact that made Ishmael and his friends do that? Was it for their own benefit, due to the situation they're in?

Are you referring to Chapter 13?

The company sets up an ambush in the forest and await the passing of rebels. Eventually they spot some people wandering through the forest; when it is clear that armed rebels are among the people, the Lieutenant Jabati gives the order and they open fire. Beah discovers that his trigger finger is numb and he cannot fire his weapon. Beah’s other tent-mate, Josiah, is knocked onto a tree trunk by an RPG shell, breaking his back. Beah also sees Musa, dead from a head wound. At this moment, Beah manages to fire his G3 weapon and kill a man. He envisions the massacres he has seen the rebels perpetrate in the past, fueling his anger and bloodlust. He continues killing everyone he sees, stopping only to take ammunition, weapons, and supplies from their corpses.

The nightmare Beah experiences that night underscores the turning point for the young man in his shift from childhood to forced maturity. He has seen his friends die at the hands of rebels - up to this point, every offence the rebels committed in his sight had been against strangers - and now can unleash his pain and hatred on a visible target. From that point on, he has no difficulty identifying the rebels as inhuman enemies to be killed on sight.

Thank you Aslan!Can you answer my question(s) now?