The carnage of World War I gave rise to liberal visions for a new world order with democratized foreign policy and informed international public opinion. Conservatives emphasized continuity in national sovereignty, while socialists focused on the interests of the working class. While British diplomacy in the construction of the League of Nations has been widely discussed, we focus on contemporary uses of nationalism and internationalism in parliamentary and press debates that are more ideological. We also examine how failed internationalist visions influenced uses of these concepts during World War II, supporting alternative organizational solutions, caution with the rhetoric of democracy and public opinion, and ways to reconcile national sovereignty with a new world organization. The United Nations was to guarantee the interests of the leading powers (including the United States), while associations with breakthroughs of democracy were avoided. Nationalism (patriotism) and internationalism were reconciled with less idealism and more pragmatism.