I began this study as the United States was extricating itself from its longest and most unsuccessful war, and I am ending it as Americans are recovering from the deepest recession of the post-World War II era. The Vietnam War stimulated widespread public interest in the origins of the Cold War while our recent difficulties have caused many Americans to ask how we ever became so vulnerable to external economic developments. During the late sixties and early seventies, historians associated with the "revisionist" school raised the level of the national debate by reemphasizing the importance of economic factors in American foreign policy. Among other things, these scholars demonstrated that the United States assumed world-wide commitments after 1945 out just to stop Communist expansion, but to defend certain economic interests, both material and ideological, as well.