American foreign policy since 1945 has been made by the often cumbersome processes of response of a representative republic to very rapidly acquired responsibilities as a world power. It involves the story of the transformation of an isolationist citizenry, who had frequently assumed that international order was of no vital concern to it, or that the order would be maintained automatically, or that American efforts to maintain world order could end only in disaster because of the inadequacies of American leaders and the sophisticated deviousness of foreigners. The transformation of a largely isolationist citizenry into the consenting citizens of a republic facing the demands of world rivalry has the epic sweep of a decisive world historical movement. The magnitude of the effort involved, however, dwindles when the dimensions of the challenge to the republic are considered.