The A to Z of U.S. Diplomacy from the Civil War to World War I provides a convenient introduction to a critical period of American diplomacy. The half-century from 1861 to 1914 formed a crucial time in the development of the American approach to the world, for the United States laid the foundations for its 20th century foreign policy. While the famed Monroe Doctrine insisted that no foreign power meddle in the American continent, it did not stop the U.S. from waging war against Spain, mixing in conflicts in Cuba, Chile, and Mexico, nor in backing independence for Panama, all the while acquiring smaller Pacific islands.