In responding to the death, Jack takes an entirely different direction from logic or common sense, in direct conflict with the actual events they had all witnessed. Perhaps acting out of some guilt he is unable to acknowledge, Jack becomes paranoid, posting guards at the entrance to the castle rock area in case any of Ralph's tribe tries to enter. One of the boys questions this concern and Jack replies, "They'll try to spoil things we do." Ironically, he is also taking the part of the true beast, the Lord of the Flies, who told Simon not to try and stop the "fun" that was going to take place on the island.
The entrance guards serve another purpose as well — to protect the tribe from the beast. Jack tells his tribe that they did not, in fact, kill the beast, just beat it as it came in disguise. Therefore, they still need to appease it and be on the alert. He prescribes their reality now as he had dictated their dreams and emotions in the previous chapter. This technique for truth control is standard in tyrannical regimes. Because none of the boys want to admit their participation in the "obscene" dance, they allow Jack to dictate their reality. They find comfort in his overbearing authority, as if he can protect them from their indefinable fears through strength of his personality alone. More concretely, Jack offers them the protection of weaponry and an instinct for warfare. When Roger sees the boulder that stands ready to crush interlopers at the entrance to Castle Rock, he deems Jack "a proper chief" because he's got weaponry, the makings of war.
For a sadist like Roger, joining the tribe offers him the chance to unleash his cruelty amidst Jack's reign of "irresponsible authority." All his life, Roger has been conditioned to leash or mask his impulses, as evidenced by his inability to actually hit Henry with the stones in Chapter 4. Hearing that Jack has had Wilfred arbitrarily bound and left to wait hours for punishment strikes a responsive chord in Roger. By the end of the next chapter, he carves out a distinct niche in the tribe as the hangman, the torturer who plays a key role in all dictatorships.
Jack doesn't consider himself "a chief . . . in truth" until he accomplishes the theft of Piggy's glasses. In this way, Jack symbolizes a twisted Prometheus, stealing fire from the humans to profit the savages as opposed to stealing from the gods to benefit humans. Note that originally he and his group of choirboys were to play the role of Prometheus in maintaining the fire, maintaining a visual plea to civilization for rescue and quick return home.
Ralph's connection with his civilized self fades even more rapidly now, although he fights to maintain it and is baffled by the "curtain" that seems to fall when he tries to stress the importance of the fire. When the twins question the value of keeping the fire lit, Ralph "tried indignantly to remember. There was something good about a fire." Piggy, of course, instantly knows what this good is, as his connection to civilization remains very strong because it offers him protection that is lacking on the island.
Piggy is so intent on preserving some remnant of civilization on the island that he not only remains loyal to Ralph but to the concept of civilized discourse represented by the conch. He assumes, improbably enough, that Jack's raiders have attacked them to get the conch. Just as he takes for granted that Ralph has not lost his focus on rescue and home, he figures that Jack still places a value on what the conch represents when obviously Jack has abandoned all that, preferring the life of savagery. Jack's leadership is based on fear; he has abandoned the conch for the dance.
The loss of his glasses to the savages literally renders Piggy more helpless and ineffectual and symbolically deprives Ralph of his intellectual counselor. The alert reader understands that Piggy will be the next victim.
gesticulate to make or use gestures, esp. with the hands and arms, as in adding nuances or force to one's speech, or as a substitute for speech.
torrid so hot as to be parching or oppressive; scorching.
Reds [Slang] Communists.
lamp standard lamppost.
barmy [Brit. Slang] crazy.
round the bend [Brit. Informal] crazy; insane.
bomb happy [Slang, Chiefly Brit.] crazy; insane.
crackers [Slang, Chiefly Brit.] crazy; insane.
pills [Vulgar Brit Slang] the testicles.
bowstave here, slightly curved arc like that of a bow.