European Union follows European Atomic Energy Community
Treaty of Rome (1958‍–‍1972)
In 1957, Belgium, France, Italy, Luxembourg, the Netherlands, and West Germany signed the Treaty of Rome, which created the European Economic Community (EEC) and established a customs union. They also signed another pact creating the European Atomic Energy Community (Euratom) for cooperation in developing nuclear power. Both treaties came into force in 1958. Although the EEC and Euratom were created separately from the ECSC, they shared the same courts and the Common Assembly. The EEC was headed by Walter Hallstein (Hallstein Commission) and Euratom was headed by Louis Armand (Armand Commission) and then Étienne Hirsch (Hirsch Commission). The OEEC was in turn reformed in 1961 into the Organisation for Economic Co-operation and Development (OECD) and its membership was extended to non-European states, the US and Canada. During the 1960s, tensions began to show, with France seeking to limit supranational power. Nevertheless, in 1965 an agreement was reached, and on 1 July 1967 the Merger Treaty created a single set of institutions for the three communities, which were collectively referred to as the European Communities. Jean Rey presided over the first merged commission (Rey Commission).
comes after comes next ensues