In Lord of the Flies, Jack allows himself to be drawn into the violent nature of the island. In very short time, Jack transitions from proper English choir boy to savage chief. The first major incident that tempts Jack's violent nature is when he catches the piglet on one of the very first days. In the crucial moment, Jack stalls and cannot cut the piglet's throat. The other boys, Ralph and Simon, weigh "the enormity of the knife descending and cutting into living flesh" (31). Jack becomes extremely embarrassed about his inability to kill the piglet and swears that "next time there would be no mercy" (31). The other boys' censure motivates Jack as much as his own personal desire to make the kill. His role as hunter for the tribe hinges on his ability to hunt and eventually to kill, just as his role as head choir boy relied on his ability to sing C sharp.
When Jack finally makes his first kill, he wishes to make "a nick in the hilt" of his spear as proof of his kill (69). For Jack, this success and provision of meat to the tribe is a matter of pride. He boasts to the other boys "there were lashings of blood...you should've seen it" (69). With his first kill, Jack has taken ownership of his own "gift for the darkness"--a gift for violence and an ability to kill. His penchant for using violence escalates from this point on; shortly thereafter, Jack "smacked Piggy's head" and the "glasses flew off and tinkled on the rocks," breaking one of the lenses (71).
Jack latches onto violence and uses it to control the other boys in a way that his popularity could not. At the beginning of the novel when the other boys on the island would follow Ralph because of sheer regard and esteem, Jack could only get obligatory votes from the choir. Jack realizes very quickly that violence was a way of dominating the other boys and gaining the power that he so craved. He comes to rely on it more and more, until his savage side has completely overshadowed any of his finer qualities, reason, or logic.