- 1951: European Coal and Steel Community (ECSC) is founded by the Treaty of Paris. The members are West Germany, France, Italy, Belgium, Luxembourg and the Netherlands. The UK declines an invitation to join.
- 1957: Two further organisations are formed: the European Atomic Energy Community (Euratom), and the European Economic Community (EEC). The latter is set up under the Treaty of Rome. Both are made up of the same six countries as the ECSC.
- 1960: A rival body – the European Free Trade Association – is formed by Austria, Denmark, Norway, Portugal, Sweden, Switzerland and the UK. Like the EEC it seeks to establish free trade, but avoids the creation of supranational institutions.
- 1961: The UK submits its first application to join the EEC, under Conservative PM Harold Macmillan.
- 1963: The British application is vetoed by the French President, Charles de Gaulle.
- 1965: A Merger Treaty is signed, combining Euratom, the EEC and ECSC into one body, the European Communities.
- 1967: The UK makes a second application, under Labour PM Harold Wilson. Again, it’s blocked by de Gaulle.
- 1968: A customs union is completed by the six members of the EEC, removing all import duties between them.
- 1973: The UK makes a third – and successful – application, this time under Conservative PM Edward Heath. Joining alongside Britain are Denmark and Ireland. Norway also applies, but it does not join, after a referendum on membership.
- 5 June 1975: The UK holds a referendum to confirm its continuing membership of the EEC, following a renegotiation led by Labour PM Harold Wilson. The British people vote to stay in by 67% to 33%.
- 1979: The first elections to the European Parliament are held.
The Exchange Rate Mechanism is launched. Its aim is to harmonise exchange rates across the EEC, in preparation for the adoption of a single currency.
- 1981: Greece joins the European Communities, as the first stage of the Mediterranean Enlargement.
- 1984: Conservative PM Margaret Thatcher negotiates a rebate on Britain’s contribution to the EC budget.
- 1981: Spain and Portugal complete the Mediterranean enlargement, joining the European Communities.
- 1985: The Schengen Treaty is signed, creating a borderless zone across most of the member states. The UK doesn’t sign up.
- 1986: The Single European Act is signed, launching an ambitious plan to create a single market by the end of 1992.
- 1992: The Maastricht Treaty is signed, creating the European Union – into which was the EC was rolled. It also sets the foundations for the single currency, and establishes cooperation in foreign and security policy.
- 1995: Austria, Finland and Sweden join the European Union. Norway and Switzerland had also applied, but both withdrew after membership was rejected in national referenda.
- 1997: The Amsterdam Treaty is signed, further developing security policy and starts the process of developing employment and social protection policies.
- 1998: Accession talks are opened with Cyprus, the Czech Republic, Estonia, Hungary, Poland and Slovenia. A year later Romania, Slovakia, Latvia, Lithuania, Bulgaria and Malta follow suit.
- 2001: The Nice Treaty is signed, reforming the EU’s institutions and reinforcing cooperation in defence and judicial policy.
- 2002: Euro coins and notes become the legal tender of the EU member states participating in the single currency.
- 2004: The largest single enlargement of the EU sees ten new members: Cyrus, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia and Slovenia.
- 2005: A move to create a constitution for the EU is abandoned, after being rejected by referendums in France and the Netherlands.
- 2007: The Lisbon Treaty is signed, significantly extending the powers of the European Parliament and strengthening the European Council.
The remaining two countries from the 1999-2000 accession talks – Romania and Bulgaria – join the EU.
- 2009: The Eurozone Crisis flares, following the broader economic problems brought about by the global financial crisis.
- 2015: The Migrant Crisis begins: refugees and migrants travel into the EU via the Mediterranean, or through south-east Europe, seeking asylum. Many are fleeing armed conflict in the Middle East.
Produced by The UK in a Changing Europe
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For more reading, look at our fact profile on when Britain decided to join the EU or this one on why the UK did not join earlier.