Why do Jack's boys attack Ralph?

Jack has turned the boys against Ralph; since they are completely under his control, he punishes them for no reason and makes them do his bidding. They attack Ralph when he is sleeping and beat him badly. They would kill Ralph if Jack told them to; he has convinced them that the "beast" can assume any shape and that they did not kill Simon; rather they killed the "beast."

I need help answering why did the boys attack Simon in Lord of the Flies Chapter 9 NEED SEVERE HELP!!!!!