Chapter Four contains the turning point of Ralph and Jack's relationship. Whilst previously Jack had respected Ralph's leadership despite some initial strains over such issues as hunting vs. helping with hut building, by the end of Chapter Four the situation had substantially changed. Jack is flushed with success after finally killing a pig, and the humiliation he feels over Ralph's admonishment over neglecting the fire is more than he can bear. The reenactment of the hunt is both a way for Jack to escape Ralph's brooding anger and to relive the primal joy he felt from the first successful hunt.
Ralph is intensely annoyed and frustrated by the neglect of the fire, and only being able to stand by and watch as the boys perform their reenactment of the hunt only further darkens his mood,
Then Maurice pretended to be the pig and ran squealing into the centre, and the hunters, circling still, pretended to beat him. As they danced, they sang.
"Kill the pig. Cut her throat. Bash her in."
Ralph watched them, envious and resentful. (p.94)
The author includes the reenactment of the first successful hunt to both highlight the huge rift between Jack and Ralph, and to show how the boys through their chanting and actions are moving beyond just playing a game; the violence and bloodthirsty nature of killing a wild beast is not something they recoil from but rather embrace with wild enthusiasm. The reenactment of hunting represents a dark foreboding of what will come in later events.
This is a analysis about the hunt on the Lord of the Flies study guide from enotes.com
Ralph’s well-intentioned plans go horribly awry when the hunters abandon the signal fire to follow Jack after a pig. As a result, their first chance for rescue is missed. Jack downplays this by focusing on his triumphant hunt, but this only serves to alienate Ralph. Ralph is then put in the unfortunate position of having to criticize the hunters’ success. He is frustrated because his plan would have worked had it been carried out. He is losing his power to maintain order on the island. In addition, his belief in the responsibility of the fire produces no tangible result (despite the fact that it was the hunters who failed), whereas Jack quite effectively shows his use of fire by roasting the pig and feeding the others with meat.
-enotes.com (Chapter 4 Summary and Analysis)