A republic in central Europe, Austria was the center of the Hapsburg Empire, which during the 16th to 19th centuries controlled (at one time or another) Hungary, Czechoslovakia, Belgium, the Netherlands and large portions of Yugoslavia, Poland, Romania, Italy and Germany. After 1815, Austrian power declined with the growth of nationalism among its subjects. In 1867, the Austro-Hungarian dual monarchy was created to appease Hungarian nationalists, but the government resisted similar concessions to other national groups. The assassination of Archduke Francis Ferdinand, heir to the Austro-Hungarian throne, in Sarajevo, Bosnia, on June 28, 1914, began the series of events that quickly led to World War I. During World War I, Austrian troops were active in the Balkans, Romania, Poland, Russia and Italy, but by October 1918, Austria's armies were routed, and the monarchy collapsed. The empire dissolved rapidly, and Austria emerged much reduced in size, representing the German-speaking area of the empire. In 1918 the republic of "German Austria" was formed, and there was considerable sentiment for union with Germany. By the Treaty of St. Germain (1922), such a union was expressly forbidden, and the country's name became simply "Austria." During the 1930s, an Austrian fascist regime attempted to maintain independence, but in March 1938, Germany invaded and quickly occupied the country, merging it into the Third Reich with only a token protest from the Allies. After Germany's defeat in World War II, the Austrian Republic was re-established, and the country was divided into zones of occupation by the United States, the Soviet Union, Britain and France. In 1955, foreign troops were withdrawn, and Austria proclaimed its political neutrality. Austria maintains close economic ties with much of western Europe.