For the first time in Lord of the Flies, Ralph knows fear, recognizing that the savagery of the boys has arisen to dominate their actions.

It is more than a little difficult to figure out what you are asking, but this point in the book comes as Ralph starts to see how the boys are changing and how they are drawn to Jack's "tribe" as they get to act out the savage tendencies within them.  His fear is mainly that of the loss of control and the sense that somehow he has to hold things together so that they can be rescued, so that if adults were to come to the island they could be proud of the boys.

Of course, as time goes on, the fear comes to completely dominate the boys and drives them to further and further depravity, particularly in the case of Roger.