The Merger Treaty marked a significant milestone in the evolution of European integration by creating the European Community through the merger of existing institutions. Prior to this, three separate organizations facilitated cooperation among European nations: the European Economic Community (EEC), established in 1957 to expand economic cooperation, the European Coal and Steel Community (ECSC), created in 1951 for managing coal and steel industries, and the European Atomic Energy Community (EURATOM), founded in 1957 to promote nuclear energy. The challenges of the post-World War II era prompted European leaders to think about greater political and economic cohesion. The Merger Treaty, signed on April 8, 1965, officially came into effect on July 1, 1967, and was aimed at simplifying governance and enhancing unity. It combined the executive bodies—the Commission and the Councils—of the three communities into a single set of institutions, streamlining decision-making processes, and representing a commitment to a unified Europe.

This newly established framework greatly facilitated common policies for agriculture, trade, and economics across member states. Additionally, the Merger Treaty paved the way for further treaties, notably the Single European Act in 1986 and the Treaty of Maastricht in 1992, which expanded the ambitions of European integration to include monetary union and the formation of the European Union. The effects of this treaty resonate in contemporary European politics and economics, illustrating the foresight of nations working together for lasting peace and prosperity in a historically fragmented continent.