After suffering through centuries of bloody conflict, the nations of Western Europe finally unite in the spirit of economic cooperation with the signing of the Maastricht Treaty of European Union. The treaty, signed by ministers of the European Community, called for greater economic integration, common foreign and security policies and cooperation between police and other authorities on crime, terrorism, and immigration issues. The agreement also laid the groundwork for the establishment of a single European currency, to be known as the “euro.” By the time the Maastricht Treaty took effect in 1993, it had been ratified by 12 nations: Great Britain, France, Germany, the Irish Republic, Spain, Portugal, Italy, Greece, Denmark, Luxembourg, Belgium, and the Netherlands. Since then, Austria, Bulgaria, Finland, Sweden, Cyprus, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Romania, Slovakia, and Slovenia have also joined the union. The euro was introduced into circulation on January 1, 2002. In June 2016, in what became known as “Brexit,” the United Kingdom voted to leave the European Union. They UK officially severed ties with the EU on January 31, 2020 and entered an 11-month transition period.