As World War II came to an end, Europe became indelibly divided into east and west. Eastern Europe became the countries occupied by the Soviets when they expelled the Germans from this land as they moved their army toward Germany. Western Europe was mostly defined as the lands liberated by the British and American forces, as well as some countries that had remained neutral in the conflict, such as Spain and Switzerland. Germany was split in two, with one-quarter of the country remaining under Soviet influence while the rest of the country was re-established as a democracy.

What happened in Eastern and Western Europe after World War II would define the playing field of the Cold War. Western European countries were largely democratic, while Eastern European nations mostly had socialist governments that were mere puppet regimes of the Soviet Union. The division between East and West would be called the "Iron Curtain" after a speech given by former British Prime Minister Winston Churchill in 1946.

Further divisions between Eastern and Western Europe were made in 1949 with the founding of NATO (North Atlantic Treaty Organization). This multinational military alliance consisted mostly of countries in Western Europe and North America. They sought to support each other should any member nation be attacked. Although the treaty did not state so specifically, NATO was meant to be a protective pact should Eastern Europe try to move the Iron Curtain further west. The Eastern European countries responded in 1955 with the Warsaw Pact. This was a similar treaty between the Soviet Union and its various satellite states. In many ways, the divisions between Eastern and Western Europe can be seen by looking at which countries were members of these treaties, although a number of European countries did not sign on to either treaty.