The United States’ entry into World War II brought an end to over two years of debate across the nation. With the attack on Pearl Harbor, American anti-war sentiment dissolved almost overnight not only in Congress but also amongst the general public. The ‘great debate’ between the isolationists and interventionists was over, and isolationist sentiment disappeared. In the eyes of the internationalist movement, the purpose of American involvement in the war was clear. For them, the war represented a second chance for the United States to play a significant role in an international organisation, which had been the primary aim of most internationalists since the US rejection of the League of Nations in 1920 and the setting up of the League of Nations Non-Partisan Association in 1923. It was clear that a great deal of research and education would be necessary to ensure that any future international organisation would be acceptable to the American people.