In September 1963, two months before his death, John F. Kennedy mused aloud to his old friend the journalist Charles Bartlett about the prospects for the 1968 presidential election, in which, he presciently worried, his brother Robert might run against Lyndon Johnson. “He gave me the feeling he wasn’t pleased,” Bartlett would recall years later. “He wanted a record of his own. I sensed that he wanted the Kennedy administration to be Jack, and Bobby was going to turn it into a succession thing. Jack didn’t want a dynasty, although I am sure his father would have wanted that.” By...