What comparison is implied at the end of "Lord of the Flies"?(Look at “end of innocence” line and also think about where these boys will be going)
I think what your question is driving at is the comparison between the atrocities the boys commit on the island, and the continuing atrocities of war outside the world which surrounds them. We know that the boys' planes was shot down, that their civilisation was "in ruins", adn that the parachutist is shot down in an air battle. There's a war going on.
Ralph cries. And then...
...the other little boys began to shake and sob too. And in the middle of them, with filthy body, matted hair, and unwiped nose, Ralph wept for the end of innocence, the darkness of man’s heart, and the fall through the air of the true, wise friend called Piggy.
"The end of innocence" is often associated, in Britain, with World War I. Pre 1914, England was in the Edwardian era, often characterised as an "age of innocence". War ended it. And war, of a sort, ended the innocence of the boys on the island. The darkness of man's heart, the blackness within, the fear of the beast and of each other, caused everything to break down into violence. And Piggy was killed in the violence - Piggy, who represented clear-sightedness, democracy, honour, wisdom.
The officer grinned cheerfully at Ralph.
“We saw your smoke. What have you been doing? Having a war or something?”
There has been a war on the island, just like on the outside. And the boys are now going to return to that world, to one lot of mindless violence to another. And look at how Golding ends the novel:
[The officer] turned away to give them time to pull themselves together; and waited, allowing his eyes to rest on the trim cruiser in the distance.
The camera pulls round, away from the boys, away from the officer, and towards the sea. It rests on the military ship with its sub-machine gun. And the novel ends. Couldn't be clearer, really, could it?