In the first chapter of Lord of the Flies, what examples in the text show why the boys were on the plane?

The boys are on the island because they have been evacuated by plane from England, which is experiencing a nuclear war. Although this is never stated explicitly, there are many clues. First, the plane was full of young boys without their parents, and many of the boys don't know each other. The first thing Piggy asks is, "Where's the man with the megaphone?" indicating that a man the boys didn't know was in charge of getting them on the plane. Piggy also explains that their plane was attacked, resulting in the crash landing and the "scar" on the island that the cabin made as it traveled through the jungle. Ralph believes his father will rescue them, but Piggy points out that he overheard the pilot of the plane say that an atom bomb struck the vicinity of the airport after they escaped. "They're all dead," he informs Ralph. When Ralph finds the conch and Piggy instructs him how to blow it, they use it to call the surviving boys. Piggy then moves through the crowd of assembled boys asking names, and the boys "gave him the same simple obedience that they had given to the men with the megaphones." This suggests they had recently been in a large staging area for evacuees where men had done the same thing Piggy is now doing.