In Lord of the Flies, Ralph has been voted as leader after having called all the boys together using the conch. The conch is the symbol of democracy and good order and it is significant that Jack has never really had any respect for it, especially when it is Piggy who is holding it.
The boys are obsessed with the possibility of there being a beast on the island and they have imagined it as a "snake thing" (ch 2) or as a creature that comes out of the sea (ch 5) and by chapter 8, even Ralph is convinced about the presence of a beast with "teeth...and big black eyes." There is much disagreement and name calling and Jack says he can no longer be a part of the group if Ralph is chief. He storms off.
He has a small group of boys who go with him and he tells them that they will hunt and that he will be chief of this new tribe. Jack talks about the beast and that they should stop worrying about it. Jack also mentions that they are unlikely to dream as much in their new camp because it is near the end of the island. He intends to get more followers, he says by killing a pig and having a feast. He even says that they will leave some of the "kill" behind for the beast so that it will not bother them further.
Having located the pigs, Jack "instructed his hidden hunters." He makes sure they all understand him and they goes in for the kill. They will need fire so Jack intends to "raid them (Ralph's group) and take fire." He also keeps his word about leaving something for the beast and tells Roger to sharpen a stick, after which he impales the pig's head on the stick, announcing that it is "a gift" for the beast.
Jack tells his new tribe that they will invite all of the others to feast upon their meat at their camp on the beach. He also says that they will need to steal the fire in order to keep their camp alive and well and that they will offer the pig's head from their most recent hunt to the beast as a thank you for a successful hunt.