The genesis of the integration process began in Europe after the World War II. In the process of planning the introduction of a new political order in post-war Europe, it was acknowledged that the key task was the reconstruction of European economies. Western European leaders realised that only efficient and effective European economy would be a foundation on which new safety and development structures could be built. The American aid plan for Europe – the European Recovery Plan, called the Marshall Plan, was a great support for those plans. At that time the actions of the Soviet Union, a former ally, which after the war began violently affirm its supremacy in the controlled area of Central and Eastern Europe, openly promoting antidemocratic communist ideology, became disturbing and at the same time mobilizing the Europeans. Only common, coordinated actions could provide European countries with the force with which Western Europe could resist the Soviet influence and the economic dominance of the United States of America. The post-war years were the time of formation of a new, bi-polar political configuration in Europe and in the world (the East – the West), which led the world to a new confrontation, this time a nuclear one. On one side there were Western democracies, on the other side the totalitarian Soviet Union and its subordinated satellite states building a military eastern block hostile to western democracies. This configuration had a decisive influence on the post-war European integration process and constituted mobilization for Western societies to undertake a firm integration action. History of European Integration. The post-war European integration process began with the reconstruction of Western European infrastructure and the economies. Appropriate stimuli for its start proved to be the economic agreements and organizations set up at the end of the forties of the twentieth century: the Benelux Customs Union, the Treaty of Economic, Social, and Cultural Collaboration and Collective Self-defence and the Organization for European Economic Co-operation.