During the past 25 years, the foreign policy of the United States has changed dramatically from the darkness of isolation to the bright sunlight of world leadership and responsibility. As the foreign policy of the United States has shifted, the requirement for military participation in world affairs has increased in importance. It is quite obvious that the increase in the importance of the military in world affairs has not been accidental. The need for the power of the armed forces has existed in the United States from the day of its origin. The degree to which this power is required depends upon the nature of the intercourse with other countries in the diplomatic arena. This book discusses selected periods of United States history which have influenced the development of the nation as a world power. Primary emphasis is placed upon the influence of the armed forces upon the implementation of the American foreign policy.