The reconstruction era (1920–21) after World War I created a new map of Europe, accompanied by a series of complex territorial disputes. Germany (the Weimar Republic) was stripped of 25,000 sq. miles (65,000 sq. km) of territory. On Germany’s eastern and northern borders, the Treaty of Versailles resorted to plebiscites, to resolve the determine borders in Schleswig, East Prussia and Silesia; from 1920, the Saar region was to be governed by the League of Nations for 15 years, with France given control of its coal mines. Along the western borders of the nascent Soviet Union (USSR) a string of uprisings concluded in 1920–21 with the formal recognition of the independence of Finland and the Baltic states. Hungary, Poland, Romania and Czechoslovakia all resorted to armed conflict to further irredentist territorial claims. The Italians withdrew from Albania in 1920 and Switzerland was declared neutral by the League of Nations in 1920. A particularly vicious war was fought between Greece and Turkey, with civilian massacres perpetrated by both sides, while the Irish war of independence was also at its height during this period. The flood of demands for national self-expression challenged the League of Nations’ powers of arbitration.