Merger Treaty: The European Community is formally created out of a merger between the Common Market, the European Coal and Steel Community, and the European Atomic Energy Commission.

The Merger Treaty, also known as the Treaty of Brussels, was a European treaty which unified the executive institutions of the European Coal and Steel Community (ECSC), European Atomic Energy Community (Euratom) and the European Economic Community (EEC). The treaty was signed in Brussels on 8 April 1965 and came into force on 1 July 1967. It set out that the Commission of the European Communities should replace the High Authority of the ECSC, the Commission of the EEC and the Commission of Euratom, and that the Council of the European Communities should replace the Special Council of Ministers of the ECSC, the Council of the EEC and the Council of Euratom. Although each Community remained legally independent, they shared common institutions and were together known as the European Communities. This treaty is regarded by some as the real beginning of the modern European Union.