The Carinthian plebiscite (Kärntner Volksabstimmung, Koroški plebiscit) was held on 10 October 1920 in the area in southern Carinthia predominantly settled by Carinthian Slovenes. It determined the final border between the Republic of Austria and the newly formed Kingdom of Serbs, Croats and Slovenes (Yugoslavia) after World War I. The predominantly Slovene-speaking plebiscite area voted to remain part of Austria with a 59% majority.
Austrian-Slovene clashes in Carinthia
After the defeat of the multi-ethnic Austria-Hungary and the ruling Habsburg dynasty in World War I, new states arose in its former territory. Among these there was an internationally unrecognized State of Slovenes, Croats and Serbs, which was created in the final days of the war according to the 1917 Corfu Declaration, and merged with the Kingdom of Serbia to form the Kingdom of Serbs, Croats and Slovenes on December 1, 1918.
Determination of borders between the new countries was complex and difficult, and not always peaceful: While the northwestern border with the Kingdom of Italy along the "Julian March" was already determined by the 1915 Treaty of London, the demarcation line between Yugoslavia and the rump state of German-Austria was a difficult and highly disputed matter. The principle of self-determination, championed by U.S. President Woodrow Wilson, was taken up by both Slovenes and German-Austrians in the Carinthian, Styrian and Carniolan lands of the defunct Habsburg empire. The rising tensions culminated in clashes of arms, as on Marburg's Bloody Sunday in Lower Styria and the continued fighting of paramilitary groups in southeastern Carinthia.
In particular the "Carinthian question" had become an issue in the closing days of World War I, when events developed rapidly, beginning with territorial claims by the Slovenian National Assembly on October 17, 1918. These claims were rejected by the Carinthian provisional Landtag assembly on 25 October 1918, declaring the state's accession to German-Austria.