What effort of does Ralph make towards jack?

Chapter 12, Jack attempts to burn down the island, killing Ralph. The Naval officer arrives just in time. If he hadn't shown up, then Ralph would have most likely been kiled, and the island would have been run by savages. An alternative answer to WHY Jack trys to kill Ralph is that Jack knows that while Ralph remains alive his own claim to leadership is very weak. Ralph was elected to be the leader and later when Jack tried to force a second election Ralph was reafirmed as leader. Like many egocentric people Jack judges other people by his own standards. He has always shown that he is unable and unwilling to allow someone else to be leader and he assumes that Ralph would think the same way and would plot to over throw him. So, for Jack the, only way of permanently removing the rightful leader, who is also his only serious rival, is to kill him.