Hard-won but vital: EU enlargement in historical perspective

Enlargement has become one of the defining features of the European integration process. This was neither foreordained nor predicted by those who drafted the Treaty of Rome between 1956 and 1957. The founding fathers mentioned the possibility of countries joining in the Treaty preamble. They also included Article 237, which provided more detail on the procedure for new countries to join. But nothing in the historical record indicates any realisation on their part of how central the expansion of the European Community (EC)/EU would be to the integration process. Still, in the sixty years of subsequent development, ‘widening’ has in many ways had the most dramatic impact on the process that the Treaty set in motion.