Snapshot

The European Union is the visible result of a decision made in May 1950: that lasting peace on the continent depended on tying together the heavy industries that fuelled twentieth-century war. From that single technical move (pooling coal and steel) the Union grew outward in widening rings — six countries became twenty-seven, a single market became a single currency, a customs club became a foreign-policy actor. The institutional present is incomprehensible without that step-by-step logic.

Legal Anchors

• •TEU Preamble and Article 1 — establishment of the Union, indissoluble nature of integration.
• •TEU Article 49 — accession clause used by every joining state since 1973.
• •TEU Article 50 — withdrawal clause used by the United Kingdom in 2017.
• •Full consolidated TEU (OJ C 202, 7.6.2016) and TFEU.

Why It Matters

Three pieces of present-day EU design only make sense in light of the post-war history: (a) the Commission's privileged role as "engine," which descends directly from the High Authority of the 1951 Coal and Steel Community; (b) the persistent unanimity rule in foreign policy, which reflects the bargain made when France and others were unwilling to surrender sovereignty in security; (c) the recurring tension between "deeper" and "wider" Europe, which is the unbroken thread from Maastricht (1992) through the Big-Bang enlargement (2004) to Ukraine's accession negotiations in 2026.

Core Concepts — Reorganised by Theme

1. The peace-through-interdependence idea. The intellectual core, sometimes called the Monnet method (or engrenage — French for "interlocking gears"), is that integration advances by linking concrete sectors; each successful link makes the next one easier and the previous step harder to undo. Jean Monnet, a French economist who had observed wartime coordination first-hand, drafted the proposal that French foreign minister Robert Schuman read out on 9 May 1950. Winston Churchill had given the rhetorical cover four years earlier in his "United States of Europe" speech in Zurich (1946), although the United Kingdom itself stayed outside for the first 22 years.

2. The institutional skeleton appears in 1951. The Treaty of Paris (signed 18 April 1951, in force 23 July 1952, expired 23 July 2002) created the European Coal and Steel Community among the Six — France, West Germany, Italy, Belgium, the Netherlands and Luxembourg. Its four organs prefigure today's EU: a High Authority (predecessor of the Commission), a Common Assembly (predecessor of the Parliament), a Special Council of Ministers (predecessor of the Council of the EU) and a Court of Justice. Coal and steel were the raw materials of war; placing them under common control made secret rearmament impractical — a structural rather than rhetorical guarantee of peace.

3. The common market is launched in Rome (1957). Two treaties were signed on 25 March 1957 and entered into force on 1 January 1958: one created the European Economic Community (EEC), with a customs union and progressive freedom of movement for goods, persons, services and capital; the other created Euratom for civil nuclear cooperation. Euratom remains in force today as a separate legal community using the same institutions as the EU.

4. Growing pains 1960s–1970s. The Common Agricultural Policy (1962) became the EEC's most expensive and most political programme. The Empty Chair Crisis (1965) — France refusing to attend Council meetings for seven months over majority voting — was resolved by the informal Luxembourg Compromise (1966): when a member state declares that "very important interests" are at stake, the Council seeks unanimity. This de facto veto right shaped Council practice for decades. The Merger Treaty (in force 1967) gave the three Communities (ECSC, EEC, Euratom) a single Commission and Council. By 1968 the customs union was complete — eighteen months ahead of schedule. In 1973 the United Kingdom, Ireland and Denmark joined: the first enlargement.

5. The Single Market shift (1985–1992). Three milestones converged. The Schengen Agreement (1985) was signed outside the Community framework by five members and began the long process of dismantling internal border checks. The Single European Act (signed 1986, in force 1 July 1987) set a hard deadline of 31 December 1992 for completing the internal market, introduced qualified majority voting for market legislation, and re-energised what had become a stagnant project. Direct elections to the European Parliament had begun a few years earlier (1979). The fall of the Berlin Wall (1989) changed the strategic horizon: a reunified Germany was about to anchor a wider Union.

6. Maastricht — the Union itself appears (1992). The Treaty signed on 7 February 1992 and in force from 1 November 1993 invented the European Union name. It introduced EU citizenship (automatic for nationals of member states), set the path to a single currency (the euro), created a Common Foreign and Security Policy as a separate pillar, and codified subsidiarity as a principle limiting EU action. Maastricht also fixed the Copenhagen Criteria (1993) for future enlargement: stable democracy and rule of law, a functioning market economy, and the administrative capacity to apply the body of EU law (the acquis communautaire). The three-pillar structure (Communities, CFSP, Justice and Home Affairs) survived until Lisbon.

7. Iterations: Amsterdam (1999), Nice (2003), the failed Constitution (2005), Lisbon (2009). Amsterdam brought Schengen into the EU framework, strengthened the AFSJ and created the office of High Representative for the CFSP. Nice prepared institutional capacity for big-bang enlargement. The Treaty establishing a Constitution for Europe, signed in 2004, collapsed after French and Dutch voters rejected it in referenda (2005). Its substance — minus the constitutional vocabulary — was repackaged as the Treaty of Lisbon, signed 13 December 2007 and in force from 1 December 2009.

8. What Lisbon actually changed. It abolished the pillar structure (the EU now has one legal personality); created a permanent President of the European Council (first office-holder Herman Van Rompuy); created the High Representative / Vice-President of the Commission as a "double-hatted" role (first office-holder Catherine Ashton); made the Charter of Fundamental Rights legally binding with the same status as the treaties; introduced Article 50 (the exit clause); introduced the European Citizens' Initiative; and gave national parliaments a formal subsidiarity-check role (the "yellow card").

Numbers & Dates

Recent Developments (2024–2026)

The arc has not stopped. Bulgaria's adoption of the euro on 1 January 2026 brought eurozone membership to twenty-one; Romania remains outside (failed convergence). The completion of full Schengen for both Bulgaria and Romania on 1 January 2025 ended a 17-year wait. In parallel, accession negotiations with Ukraine and Moldova were "technically opened" across all six clusters during the winter and spring of 2026, even though a Hungarian veto blocked the formal opening — a workaround that lets candidate countries continue substantive reform while keeping political ratification on hold.

Common Confusions

• •Council of Europe ≠ EU. The Council of Europe (founded 5 May 1949, seat in Strasbourg) is an entirely separate organisation with 46 member states. It runs the European Convention on Human Rights and the European Court of Human Rights. It is not an EU institution.
• •"Treaty of Rome" usually refers to the EEC treaty, but technically there were two Rome treaties in 1957 (EEC and Euratom). After the Lisbon renumbering, what was the EEC Treaty / Treaty establishing the European Community is now the TFEU.
• •Europe Day is 9 May (the Schuman Declaration anniversary), not 1 May.
• •The "Six" did not include the United Kingdom. The UK declined to join the ECSC in 1951 and the EEC in 1957; it only acceded in 1973.

Capsule Glossary

• •Schuman Declaration — proposal of 9 May 1950 to pool Franco-German coal and steel under a supranational High Authority. Treated as the EU's founding act.
• •Monnet method / engrenage — incrementalist integration: small concrete steps generate logical pressure for further steps.
• •Acquis communautaire — the cumulative body of EU rights and obligations (treaties, secondary law, case law, agreements) that a candidate state must adopt before joining.
• •Subsidiarity — Article 5 TEU principle that the EU acts only where objectives cannot be sufficiently achieved at member state level.
• •Copenhagen Criteria — political, economic and acquis conditions a candidate must meet (1993).
• •Luxembourg Compromise — 1966 informal agreement that the Council seeks unanimity when a member state invokes vital national interests.
• •Article 50 TEU — the exit clause introduced by Lisbon, first triggered by the UK in 2017.

Cross-References

• •Treaty hierarchy and supremacy → Chapter 2
• •The Charter and the values listed in Article 2 TEU → Chapter 3
• •Article 7 procedure (rule-of-law sanctions) → Chapters 3 and 17
• •The 2024 fiscal-rules reform → Chapter 13

Primary Sources

• •TEU (consolidated), OJ C 202, 7.6.2016 — eur-lex.europa.eu
• •Schuman Declaration — european-union.europa.eu/principles-countries-history/history-eu/1945-59/schuman-declaration-may-1950_en
• •Wikipedia, "Schuman Declaration" — en.wikipedia.org/wiki/Schuman_Declaration

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