In Chapter Eleven of Lord of the Flies, the reader witnesses the results of freedom from the restraints of a civilized society: "Jack, knowing this was the crisis, charged too." Whereas in Chapter Four, Roger has been restrained in his sadistic intents of harming little Henry by the seashore by his conditioning from his British society, he has now been released long enough from "the taboo of the old life" that he gives free rein to his innate brutality and wields his "nameless authority." It is at this point in the narrative that anarchy truly reigns.
So, if Jack is a dictator, Roger is an anarchist. Without the controls available to most dictators, such as others who can assist him in his control, Jack's leadership gives way to the anarchist, Roger, who has been waiting, waiting for the moment when he can unleash his sadism. No longer is the one restraint that has held Roger--"a civilization that knew nothing of him and was in ruins"--present to control him. He edges past the chief [Jack], "only just avoiding pushing him with his shoulder..." He realizes that he is the strongest, and he shoulders his way to the metaphoric top.