Between them, the two world wars had killed around 75 million Europeans.

While the Soviet Union suffered the largest number of casualties, there was a strong desire to establish mechanisms for co-operation in western Europe where France had been invaded three times by Germany between 1870 and 1940. Belgium had suffered the same fate on two occasions.

The carnage of the wars fought in Europe also imposed a huge economic cost.

Having enjoyed the fruits of industrialisation during the 19th century, two world wars and the intervening economic slump of the 1930s meant that by 1950, most people living in Europe were no better off than they had been in 1900.

The first tentative steps towards co-operation in western Europe were taken in May 1949 with the signing of the Treaty of London, which set up the Council of Europe with ten founding members.

The first tangible outcome came the following year with the signing of the Convention for the Protection of Human Rights and Fundamental Freedoms.

The Council now has 47 members, and continues to focus much of its efforts on the rights of individuals and the processes of democracy and justice.

The first step on the road towards economic integration was taken in May 1950 with the proposal for a European Coal and Steel Community (ECSC) to be administered by a supra-national ‘high authority’, with the purpose of pooling the coal and steel industries of participating countries.

A year later France, Italy, Germany and the three Benelux countries concluded the Treaty of Paris establishing the ECSC, which came into being in July 1952.

From the Treaty of Paris, European co-operation and pooling of sovereignty progressed through several incarnations.

In March 1957 two treaties signed in Rome set up the European Economic Community (EEC) and the European Atomic Energy Community (Euratom), both with the same six founding members as the ECSC.

The EEC established a free trade area by removing tariffs and duties on cross-border trade and also set up the Common Agricultural Policy (CAP) with the aim of ensuring an adequate supply of food and preserving the viability of rural communities.

The EEC was not, however, the only avenue towards economic co-operation. In 1960, seven countries, including the UK, established the European Free Trade Association (EFTA). As its name suggests it was concerned purely with free trade, and as such did not involve the pooling of sovereignty which was a key principle of the EEC.

Although Britain was a founding member of EFTA it was also the policy of the Conservative government of the day to join the European Economic Community (often referred to at the time as the Common Market).

• The first application to join was made in 1961, but was vetoed two years later by President de Gaulle of France, who believed that Britain’s history and economic structures made it unsuitable for membership.
• A second rejection followed in 1967, so that it was not until 1973 that the UK finally became a member.

During the 1970s and 1980s membership of the EEC grew to 12 (with the addition of the UK, Denmark, Ireland, Greece, Spain and Portugal).

The name was also changed to the European Community (EC). The scope of the EC’s activities was broadened to encompass assistance to poorer regions and the creation of a single market.

The Single European Act, which came into effect in July 1987, initiated a programme of further integration with the aim of creating a single internal market by the end of 1992.

The single market process also reinvigorated the long-standing debate about whether the EC should have a common or a single currency. At Maastricht in December 1991, a Treaty was agreed which established the European Union (EU) founded on the European Community.

The ‘three pillars’ of the EU were economic and monetary union, political co-operation, and co-operation in legal and home affairs.

During the 1990s, Austria, Sweden and Finland brought EU membership up to 15 countries.

But it also became apparent that if the Union were to expand to take in new members (mostly ex-Communist countries) from central and eastern Europe, further institutional reforms would be required.

Progress was made in this direction, with amendments to the underlying treaties being made by the Treaty of Nice (see below), which was agreed in December 2000.

At a summit of heads of government, held at Copenhagen in December 2002, it was agreed that ten new members would join the EU from May 2004.

The new members were Cyprus, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia and Slovenia.

Bulgaria and Romania subsequently joined the EU in January 2007, taking membership up to 27.