the exception of the Soviet Union, which became a superpower after World War II and maintained that status for 45 years. This left two rival ideologically opposed superpowers. After World War I, but particularly following World War II, internationalism was gaining, with the creation of the Bretton Woods System in 1944, the United Nations in 1945 and the French Union (19461958), the latter directing decolonization by possibly integrating its colonies into a European community. In this light European integration was already viewed by its proponents as an antidote to the extreme nationalism which had devastated parts of the continent. With war still raging, the Ventotene prison Manifesto of 1941 by Altiero Spinelli propagated European integration through the Italian Resistance and after 1943 through the European Federalist Movement. In March 1943, in a radio address, the United Kingdom's leader Sir Winston Churchill spoke warmly of "restoring the true greatness of Europe" once victory had been achieved, and mused on the post-war creation of a "Council of Europe" which would bring the European nations together to build peace.in 1943 for a post-war "Council of Europe" Towards the end of World War II, the Three Allied Powers discussed during the Tehran Conference and the ensuing 1943 Moscow Conference the plans to establish joint institutions. This led to a decision at the Yalta Conference in 1944 to include Free France as the Fourth Allied Power and to form a European Advisory Commission, later replaced by the Council of Foreign Ministers and the Allied Control Council, following the German surrender and the Potsdam Agreement in 1945. Aftermath (1945-1948) After the war on 19 September 1946 Churchill went further as a civilian, after leaving office, at the University of Zürich, calling for a United States of Europe. Coincidentally parallel to his speech the Hertenstein Congress in the Lucerne Canton was being held, resulting in the Union of European Federalists. Richard von Coudenhove-Kalergi, who successfully established during the interwar period the oldest organization for European integration, the Paneuropean Union, founded in June 1947 the European Parliamentary Union (EPU). To ensure Germany could never threaten the peace again, its heavy industry was partly dismantled (See: Allied plans for German industry after World War II) and its main coal-producing regions were either awarded to neighbouring countries (Silesia), managed as separate directly by an occupying power (Saarland) or put under international control (Ruhr area). The growing rift among the Four