April 16

Representatives from 16 European nations met in Paris to sign the convention forming the OEEC. Their goal was to coordinate aid distribution and promote economic recovery after World War II. The organization facilitated tariff reductions, trade liberalization, and industrial cooperation among member states. It laid the groundwork for modern European integration and eventually evolved into the OECD. By fostering dialogue and technical assistance, the OEEC accelerated reconstruction efforts. Its success demonstrated the power of multilateral economic collaboration in postwar reconstruction.

In a landmark expansion of the European Union, leaders of existing member states and ten applicant nations met in Athens to sign the Treaty of Accession on April 16, 2003. The treaty paved the way for Cyprus, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia, and Slovenia to become full EU members. This was the largest single enlargement in the EU's history, aiming to promote political stability and economic integration across post-Cold War Europe. The agreement included commitments on adopting the EU acquis communautaire and preparations for monetary union. Ratification by national parliaments followed in subsequent months, and the new members officially joined on May 1, 2004. The expansion deepened the single market and reshaped the EU's institutional structure to accommodate a larger membership.