The European Economic Community was founded in 1957, following in the ECSC's footsteps (ECSC was later merged into the EEC). In 1993, the EEC was renamed to Eu

The European Economic Community was founded in 1957, following in the ECSC's footsteps (ECSC was later merged into the EEC). In 1993, the EEC was renamed to European Community and merged into the EU. So there's direct lineage back to post-war times, and without the "baby steps" of creating close ties between significant parts of the economies (steel and coal were kind of a big deal back then) of countries that considered each other arch-foes until then (Germany and France in particular), the later initiatives might have failed, like the attempts to form the European Political Community and the European Defence Community did in the 1950s.