Lord of the Flies is a novel that shows how the boys who are stranded on the island turn into savages. Jack and his hunters become cruel. They torture a sow while hunting. They have no mercy on the sow. They cut off the head and hang it on a stick. This becomes a symbol. The head on the stick is the Lord of the Flies.
During the killing of this sow, the boys are particularly cruel. Roger puts his spear in the sow's rectum and puts all his weight on it. The pig screams in agony:
They corner the wounded pig, and when she falls they are on her. Roger is particularly cruel, driving in his spear slowly by leaning his weight upon it until the sow screams in agony. Then Jack cuts its throat. Jack begins to rub the blood on his hands onto Maurice, and then they notice Roger withdraw his spear. They become hysterical because he had pinned the sow by driving the spear through its anus.
The boys giggle and laugh hysterically. They are enjoying the blood and "colored guts" of the sow. They are intentionally mean. They have become savages. They play and reenact their acts of cruelty.
They reenact the slaughter until they grow tired.
Hunting is all fun and games. Jack flicks blood on the others. They do not properly dispose of the remains of the pig. They leave his bloody head on a stick, proclaiming it is Lord of the Flies.
As far as the naval officer is concerned, he shows up in the last chapter. He had not been observing the boys. He was passing by the island and saw the smoke from the boys' fire.