The author tests the proposition that the Vietnam War was a watershed in the history of American foreign policy by contrasting and comparing the ideas and policies of two leaders who believed in the idea of an "American mission" in history: John Foster Dulles (pre-Vietnam) and Jimmy Carter (post-Vietnam). This is an interesting, although slightly contrived, exercise. Mr. Klunk is harder on Carter than on Dulles, but he concludes that in both cases a sense of mission was an inadequate basis for policymaking.