What is the author's style in Robert Kennedy and His Times by Arthur Meier Schlesinger?

Schlesinger begins his lengthy work with a historical look at the Kennedy family's entry to America and the background of Robert Kennedy's parents. The book ends with the June, 1968 assassination. One might be lead to believe, therefore, that the work will be chronological in nature. In fact, the chronology is present, but certainly not in the strictest sense of the word.