Major Tetley is a rather unique character in this novel. Everyone else seems to have some modest commitment to society and to ethical behavior, as they are able to perceive it. Major Tetley, while he does seem to take some satisfaction from filling a leadership role (and is accused by Davies of gaining sadistic pleasure from the terrors of the three men), is really concerned only with what he thinks is his only failure — his son, Gerald. Gerald is introspective and passive and (in Major Tetley's view) girlish. For the Major, the news about Kinkaid provides one last opportunity to cure Gerald.
Major Tetley's suicide in Part 5 is likely to surprise us and leave us dissatisfied, unless we remember the extraordinary narrowness of his code. Only a personal failure is reprehensible. Gerald is Major Tetley's failure. When Gerald hangs himself, the chance to reverse his failure is finally, irrevocably taken from the Major. If he must live as a failure; he would choose to live no longer.
Major Tetley is admirably equipped. He is strong, assured, masculine, and rational. But like every other character in the book, he has a flaw. His is severe, perhaps more severe than is Davies's flaw: He lacks the conviction that all men share a responsibility for ethical behavior. His task is to "repair" Gerald; his method is lynching. It should work, but even Gil Carter knows that hanging is the business of anybody who happens to be around, so it can't work.