As Hitler prepared for and then carried out his assault on Western Europe in the late 1930s through 1941, the U.S. military was severely undermanned; the army was ranked only 19th worldwide in size. For the most part the American public followed an isolationist line, feeling that Hitler's aggression was a European problem that did not affect the United States. The Japanese attack on Pearl Harbor in 1941 abruptly ended America's isolation,...