The strategy was, and still is, to link the countries of Europe by gradually integrating their markets and economic policies. By doing so, political integration will follow. In 1968 a customs union was established among the countries of the then European Economic Community, followed by the establishment of a European single market in 1993. In order to make a single market, i.e.
ensure the free movement of goods, services, capital and labour, it was felt necessary to introduce a single currency. And as you know, this most recent step in the European integration process occurred in 1999.