The idea of European unity had roots as far back as the eighteenth century, while the term 'United States of Europe' was coined in the nineteenth. During the inter-war period serious proposals for unity were advanced by the Austrian statesman Coudenhove-Kalergi and the French politician Aristide Briand. It was not, however, until after 1945 that integration exerted an appeal which was sufficiently widespread for it to become a feasible proposition. This was due largely to the cataclysmic experience of the Second World War and to the growing belief among politicians on the Continent that nationalism needed more constraints than had been the case in the past. Various forms of collaboration therefore developed.
One was based on the more traditional style of intergovernmental co-operation. This applied to the Organisation of European Economic Co-operation (OEEC), set up in 1947 to co-ordinate the distribution of American aid through the Marshall Plan. This was followed in 1948 by the Brussels Treaty between Britain, France, Belgium, the Netherlands and Luxembourg, which in turn expanded into the North Atlantic Treaty Organisation in 1949, a traditional style of military alliance. In the same year the Council of Europe was established; comprising most of the non-Communist states of Europe, this was intended to coordinate intergovernmental negotiations on a variety of issues. Overall, however, this was not the route to integration or supranationalism or what many had originally considered the European ideal.
Instead, this began to emerge with the formation in 1951 of the European Coal and Steel Community (ECSC) between France, West Germany, Italy, and the Benelux countries. The same 'Six' expanded this into the European Economic Community and Euratom by the Treaties of Rome (1957). These allowed for a transitional period of twelve years for the establishment of a customs and economic union between the