From September 1939 to December 1941, Americans debated the role the United States should play in World War II, which was then ravaging Europe. Should America actively support the Allies, especially Britain, by providing direct financial and indirect military aid? Or should America maintain its traditional role of nonintervention? (World War I had been the sole exception.)

In 1941, the dispute intensified into what has been called the Great Debate, although the term is sometimes used to describe the entire discussion. Throughout most of the year, conflict raged in Congress, over radio waves, in print, on soap boxes, in lecture halls, from pulpits, and over kitchen tables.

Those who wanted to intervene had the great advantage of presidential power, but it is not clear which side would have prevailed had the debate continued. But on the morning of December 7, 1941, the Japanese bombed the U.S. Naval base at Pearl Harbor, Hawaii. On December 8, the United States declared war on Japan. On the 11th, Germany and Italy declared war on the United States; America reciprocated. Discussion was effectively over.