The European Union did not emerge overnight. It is the result of a deliberate, step-by-step process that began in the ruins of World War II. Understanding this history is essential for the EPSO EU Knowledge test — not just as facts to memorise, but as the logic behind why the EU is structured the way it is today.
1. The Post-War Context (1945–1950)
World War II left Europe devastated — economically, politically, and morally. Two world wars in 30 years had their roots in European nationalism and rivalry, particularly between France and Germany. The driving idea behind European integration was simple: countries that trade together and share institutions do not go to war with each other.
- 1946 — Winston Churchill calls for a "United States of Europe" in his famous Zurich speech.
- 1947 — The Marshall Plan: the US provides aid to rebuild Europe, requiring multilateral coordination. First habit of European cooperation.
- 1948 — OEEC (Organisation for European Economic Co-operation) created to manage Marshall Plan funds. Later becomes the OECD (1961).
- 1949 — Council of Europe founded (5 May). ⚠️ Not an EU institution. Separate organisation focused on human rights (European Convention on Human Rights, ECHR).
- 1950 — 9 May: The Schuman Declaration. French Foreign Minister Robert Schuman proposes pooling French and German coal and steel under a common High Authority. This date is now Europe Day.
Key Person — Jean Monnet: French economist and visionary, widely considered the "Father of Europe." He drafted the Schuman Declaration and believed integration should be built step by step — the "Monnet method" (also called engrenage: one step creates pressure for the next).
2. The Founding Treaties (1951–1957)
⚙ The Founding Period — Two Key Treaties
1951
Treaty of Paris
European Coal & Steel Community (ECSC)
In force: 23 July 1952
Expired: 23 July 2002
⚒ Coal & Steel
1957
Treaties of Rome
EEC — Common Market
Euratom — Nuclear Energy
In force: 1 January 1958
🏛 Still in force today
The Six:
🇫🇷 France
🇩🇪 Germany
🇮🇹 Italy
🇧🇪 Belgium
🇳🇱 Netherlands
🇱🇺 Luxembourg
The European Coal and Steel Community (ECSC) — 1951
The Treaty of Paris (signed 18 April 1951, in force 23 July 1952) created the ECSC among "The Six": France, West Germany, Italy, Belgium, the Netherlands, and Luxembourg. By pooling coal and steel — the raw materials of war — no country could secretly rearm.
The ECSC had four institutions that became the blueprint for today's EU: a High Authority (→ Commission), a Common Assembly (→ Parliament), a Council of Ministers (→ Council), and a Court of Justice.
The Treaties of Rome — 1957
On 25 March 1957, "The Six" signed two treaties in Rome (in force 1 January 1958):
- Treaty establishing the EEC: Created a common market — free movement of goods, persons, services, and capital.
- Treaty establishing Euratom: Cooperation on peaceful use of nuclear energy. Still exists today.
3. Early Development & the Empty Chair Crisis (1958–1973)
- 1962 — Common Agricultural Policy (CAP (Common Agricultural Policy)) established — common rules and subsidies for farming. Remains a major EU policy today.
- 1965 — "Empty Chair Crisis": France boycotts Council meetings for 7 months over proposals to extend majority voting.
- 1966 — Luxembourg Compromise: Informal agreement — if a member state declares "very important national interests" are at stake, the Council seeks unanimity. An informal veto right.
- 1967 — Merger Treaty enters into force: single Commission and single Council for all three communities.
- 1968 — Customs Union completed — 18 months ahead of schedule.
- 1973 — 1st Enlargement: UK, Ireland, Denmark join → 9 members.
4. The Single Market Revolution (1985–1992)
- 1979 — First direct elections to the European Parliament.
- 1985 — Schengen Agreement signed (outside EC framework) — beginning of free movement area.
- 1986 — Single European Act (SEA) signed (in force 1 July 1987): target to complete the Single Market by 31 December 1992; introduced QMV (Qualified Majority Voting) in the Council; first major treaty revision.
- 1989 — Fall of the Berlin Wall.
5. The Treaty of Maastricht — Birth of the EU (1992)
The Treaty of Maastricht (signed 7 February 1992, in force 1 November 1993) was the most transformative treaty in EU history.
🏛 EUROPEAN UNION
Three-Pillar Structure · Maastricht Treaty 1993–2009
⚖️
Pillar I
European Communities
EEC → EC · ECSC · Euratom
Internal market · EMU (Economic and Monetary Union)
Common policies (CAP, etc.)
Supranational
🌍
Pillar II
CFSP (Common Foreign and Security Policy)
Common Foreign &
Security Policy
Intergovernmental
🔐
Pillar III
JHA
Justice & Home Affairs
(→ AFSJ (Area of Freedom, Security and Justice) after Amsterdam)
Intergovernmental
⚠️ The pillar structure was abolished by the Treaty of Lisbon (2009) — all areas unified under a single EU legal framework.
What Maastricht created:
- The name "European Union"
- EU Citizenship — every national of a member state is automatically an EU citizen
- Roadmap to the euro and Economic & Monetary Union (EMU)
- Common Foreign and Security Policy (CFSP)
- The subsidiarity principle — EU acts only where it is more effective than member states
- Copenhagen Criteria (1993) — conditions for candidate countries: democracy/rule of law, market economy, ability to adopt EU law
6. Amsterdam, Nice & the Treaty of Lisbon
- 1999 — Treaty of Amsterdam in force: incorporated Schengen, strengthened AFSJ, created HR for CFSP.
- 2003 — Treaty of Nice in force: reformed institutions for enlargement, adjusted QMV.
- 2005 — Constitutional Treaty rejected by French and Dutch referenda.
- 2007 — Treaty of Lisbon signed (13 December).
- 1 December 2009 — Treaty of Lisbon enters into force.
Treaty of Lisbon — Key Changes:
✔ Abolished the three-pillar structure
✔ Created permanent President of the European Council (first: Herman Van Rompuy)
✔ Created High Representative / VP for Foreign Affairs (first: Catherine Ashton)
✔ Made the Charter of Fundamental Rights legally binding
✔ Introduced Article 50 — the exit clause
✔ Introduced the Citizens' Initiative (1 million signatures)
7. The Seven Enlargements
1st Enlargement
1973
United Kingdom
Ireland · Denmark
→ 9 members
2nd Enlargement
1981
Greece
→ 10 members
3rd Enlargement
1986
Spain · Portugal
→ 12 members
4th Enlargement
1995
Austria · Finland
Sweden
→ 15 members
5th Enlargement "Big Bang"
2004
CZ, EE, CY, LV, LT
HU, MT, PL, SK, SI
→ 25 members
6th Enlargement
2007
Bulgaria · Romania
→ 27 members
7th Enlargement
2013
Croatia
→ 28 → 27 (Brexit 2020)
8. Essential Dates to Memorise
| Date | Event |
|---|
| 9 May 1950 | Schuman Declaration → Europe Day |
| 18 Apr 1951 | Treaty of Paris → ECSC ("The Six") |
| 25 Mar 1957 | Treaties of Rome → EEC + Euratom (in force 1 Jan 1958) |
| 1 Jul 1987 | Single European Act enters into force |
| 7 Feb 1992 | Treaty of Maastricht signed |
| 1 Nov 1993 | Maastricht in force → EU is born |
| 1 Jan 1999 | Euro launched (11 countries, accounting only) |
| 1 Jan 2002 | Euro coins and banknotes in circulation |
| 1 May 2004 | "Big Bang" enlargement — 10 new member states |
| 13 Dec 2007 | Treaty of Lisbon signed |
| 1 Dec 2009 | Treaty of Lisbon enters into force |
| 31 Jan 2020 | UK leaves the EU (Brexit) → 27 members |
9. Key Terms
Acquis communautaire
The entire body of EU law, rights, and obligations that candidate countries must adopt to join the EU.
Engrenage / Monnet Method
Integration advances step by step — each step creates pressure and logic for the next one.
Subsidiarity
The EU acts only when objectives cannot be sufficiently achieved by member states alone (Art. 5 TEU).
Copenhagen Criteria
Membership conditions (1993): stable democracy/rule of law, functioning market economy, ability to adopt EU acquis.
Article 50 TEU
The clause allowing a member state to notify its intention to withdraw from the EU. Used by the UK in 2017.
Luxembourg Compromise
Informal 1966 agreement: when a member state declares vital national interests, the Council seeks unanimity (informal veto).