The boys are fleeing the war. They are being evacuated from the possibility of nuclear destruction:
A group of boys, being evacuated from England to Australia, crash lands on a tropical island. No adults survive the crash, and the novel is the story of the boys' descent into chaos, disorder, and evil.
The boys are young yet they are learning from the adults about the destruction and danger of war. Although war is a part of life, it shows the boys that adults have evil intentions in what should be a civilized society.
The boys are faced with their own battles when they crash on the island. Left to their own instincts, many of the boys behave as the adults who are fighting the present day war. One could say the boys have learned from the adults. War is inevitable but it also shows what society is like when there is a power struggle.
The boys face a power struggle on the island. They are having their own private war. Ralph and Jack are in a constant battle between who is going to be the chief. Even when Ralph wins the votes to be the leader, Jack is determined to over ride the popular vote and become a dictator himself.
What happened on the island has happened in the world prior to the boys crashing and landing on the island.
Today, war is still going on. There are constant battles and power struggles going on in the world today. The war on terrorism is evident of how war is inevitable. We live in a world in which power struggles happen every day. The world is not a safe place. Even in countries that appear more civilized than others, there are threats of terrorism on well governed countries.
As long as there are forces of good and evil, the war will rage on. Hopefully, good will always overcome evil, just as it did when Ralph was rescued. The sad part is that there will always be Simons and Piggys who die because of prevalent evil.