The whole nature of 'real' leadership is an acknowledgement that ultimately you, as leader, are responsible for your 'team's' success or failure.
Ralph accepts - and welcomes- the challenge of being the leader and therefore, if he was ineffective against Jack, that shows a flaw in his leadership. His father is a navy commander and would have instilled this belief into Ralph - when you lose a battle, can you blame your enemy?
Jack is tempted to refute Ralph's position as leader but, in defeat, he has recognized that, if he accepts responsibility, he must face the consequences - something he has never been able to do. The image of Jack as the choirboy adds real irony to the ending
unpainted now and wearing the remains of his choir cap
Ralph knows it is his responsibility to ensure
order, authority, dialogue, democracy
such as the conch becomes to signify. Ralph is sometimes unable to find the
right word to get their attention or galvanize them to action.
Ralph is affected by the savagery and it is only his respect for civilization that prevents him from responding to any natural instincts to kill. He too was
..carried away by a sudden thick excitement
Regarding the death of a third boy - the boy with the mulberry birthmark disappears and is assumed to have died but there is no further reference to him and his death is probably accidental - when the fire got out of control.
It seems any failure to mention a third (assumed)death is due to the overwhelming circumstances and even possibly that there are no facts to support his death. Simon and Piggy died in irrefutable circumstances and so accidental death may seem insignificance - again revealing the depth of the boys' descent from civilization - when a death is almost not worth mentioning.