In 1940, World War II was already raging in Europe and east Asia.  France fell to the Nazi blitzkrieg that spring, and Japanese forces kept grinding away in China and Indonesia.  Great Britain was alone against Axis aggression, since the other two most powerful Allied nations in that war—the Soviet Union and the United States—wouldn’t join on Britain’s side until the next year.  The Soviets had made a pact with Germany, agreeing to split Poland between the two and to allow Soviet aggression to proceed unchecked against the Baltic states and Finland.  Germany wouldn’t betray its Soviet neighbor until the following June, so Josef Stalin was content to sit the war in Europe out.  His country had gotten what it wanted—he thought. In the United States, there was a sense that entering the war was somewhere between likely and inevitable.  There had been talk about American intervention against Nazi aggression since before the war broke out, but the wil...