why do paul and kat give one of the new recruits a “hiding”?

A new recruit cant stand being in the trench anymore. Paul and his friends have to hit him to prevent him from going over, getting shot, and giving away their position.

He listens for a moment and his eyes become clear. Then again he has the glowering eyes of a mad dog, he is silent, he shoves me aside. "One minute, lad," I say. Kat notices. Just as the recruit shakes me off Kat jumps in and we hold him. Then he begins to rave: "Leave me alone, let me go out, I will go out!" He won't listen to anything and hits out, his mouth is wet and pours out words, half choked, meaningless words. It is a case of claustrophobia, he feels as though he is suffocating here and wants to get out at any price. If we let him go he would run about everywhere regardless of cover. He is not the first. Though he raves and his eyes roll, it can't be helped, we have to give him a hiding to bring him to his senses.ch 6