European Union 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 co-operation in developing nuclear energy. Both treaties came into force in 1958. The EEC and Euratom were created separately from the ECSC, although 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. Euratom was to integrate sectors in nuclear energy while the EEC would develop
European Economic Community the ECSC and Euratom were merged with that of the EEC, creating a single institutional structure governing the three separate Communities. From here on, the term "European Communities" were used for the institutions (for example, from "Commission of the European Economic Community" to the "Commission of the European Communities"). The Council of the European Communities was a body holding legislative and executive powers and was thus the main decision making body of the Community. Its Presidency rotated between the member states every six months and it is related to the European Council, which was an informal gathering of national leaders