The most general conflict of the book is survival. Here is a plane full of school-age boys who are being sent away from home because of a war. This is seen when Piggy explains, "Didn’t you hear what the pilot said? About the atom bomb? They’re all dead.” There is a major war going on outside of the plot. (This is an example of context information: outside facts about the time, place, and circumstances that affect our understanding of the story.) The boys were being evacuated and in the process ended up stranded on an island.
"'Aren’t there any grownups?' 'No.' Merridew sat down on a trunk and looked round the circle. “Then we’ll have to look after ourselves.” Secure on the other side of Ralph, Piggy spoke timidly. 'That’s why Ralph made a meeting. So as we can decide what to do.'"
They find themselves, without any adult supervision, having to learn to work together to survive. At first it sounds empowering and freeing. The boys have no adults to command them to do anything, but their fun is short-lived.
Their first step toward surviving on the island is to elect leaders. Yet, this, too, becomes a source of conflict:
"'All right. Who wants Jack for chief?' With dreary obedience the choir raised their hands. 'Who wants me?' Every hand outside the choir except Piggy’s was raised immediately. Then Piggy, too, raised his hand grudgingly into the air. Ralph counted. 'I’m chief then.' The circle of boys broke into applause. Even the choir applauded; and the freckles on Jack’s face disappeared under a blush of mortification."
Jack and Ralph wrestle for a position of power and authority. At first, they seem to be able to work together. However, as the text continues, the boys end up dividing their allegiance, some following Jack and others Ralph. At this point, the boys abandon working together to find food and shelter. Their struggle for survival becomes even more real as they begin to battle one another . . . to the death.
By the end of the text, we see how broken the boys' community was. Like the adults, fighting a large-scale atomic war, the boys end up fighting a small-scale war. Here, the author shows the evils that humans are capable of:
"He [Ralph] wormed his way through the thicket toward the forest, keeping as far as possible beneath the smoke. Presently he saw open space, and the green leaves of the edge of the thicket. A smallish savage was standing between him and the rest of the forest, a savage striped red and white, and carrying a spear. He was coughing and smearing the paint about his eyes with the back of his hand as he tried to see through the increasing smoke. Ralph launched himself like a cat; stabbed, snarling, with the spear, and the savage doubled up. There was a shout from beyond the thicket and then Ralph was running with the swiftness of fear through the undergrowth. He came to a pig-run, followed it for perhaps a hundred yards, and then swerved off. Behind him the ululation swept across the island once more and a single voice shouted three times. He guessed that was the signal to advance and sped away again, till his chest was like fire. Then he flung himself down under a bush and waited for a moment till his breathing steadied. He passed his tongue tentatively over his teeth and lips and heard far off the ululation of the pursuers."
Here, we see how Ralph has become animal-like, as he sought to stab his enemies (fellow children), with spears. The unrest, that started with a small disagreement over who would act as leader, turned into teams of boys ready to kill each other to get what they want. And, they do kill. Both Piggy and Simon are killed by the boys because of their escalating social divisions. This novel emphasizes the great evils that humanity is capable of.