What were the conditions in Europe after WWI?

In addition to the devastation of Germany, France, and England, especially London that sustained tremendous damage and 30,000 deaths from aerial attacks alone,  after the war German borders were reset.  Most of the Germans fled or were expelled from outside the territory of post-war Germany and post-war Austria.  Consequently, pre-war German provinces transferred to Poland and the Soviet Union, Czechoslovakia was established as a country as were Hungary, Romania, and northern Yugoslavia. 

With nearly 12 million ethnic Germans involved, it was the largest movement of peoples in history, and the largest in post-war expulsions in Central and Eastern Europe.  The policy that effected this movement was part of the geopolitical and ethnic reconfiguration of postwar Europe and in part retribution for Nazi Germany's initiation of the war and subsequent atrocities and ethic-cleansing in Nazi-occupied Europe.