When does the power shift into Jack's direction and why?

The power shifts in Jack's direction when he addressed the existence of the beast, something that Ralph will not do. Ralph insists there is no beast, and though Jack is wrong in saying they can hunt and kill the Beast..... he addresses it. Jack promises to hunt for the beast and protect the others from the beast, thus, the boys follow him. Jack, unlike Ralph, uses their greatest fear to gain their support.

The balance of power in chapter eight of Lord of the Flies shifts to Jack. In the beginning no one was going to switch to Jack’s side. They all think Ralph should stay leader and do not want to get rid of him. “Who thinks Ralph oughtn’t to be chief?” (Chapter 8, page 127)Jack looks around at all of the boys, but none of them move and they sit frozen. “Hands up,” said Jack strongly, “whoever wants Ralph not to be chief?” (Chapter 8, page 127) No one says anything again and Jack becomes embarrassed and leaves claiming that he is going to hunt his own pigs. However, the balance of power starts to shift when a couple of boys follow Jack later. “I expect they’ve gone. I expect they won’t play either.”(Chapter 8, Page 131) “I seen them stealing off when we was gathering wood. They went that way. The same way as he went himself.” (Chapter 8, Page 131)