State of Slovenes, Croats and Serbs
After the defeat of the Austro-Hungarian empire, the State of Slovenes, Croats and Serbs declared independence on 1 October 1918, however on 1 December 1918, Regent Alexander announced the union of the Kingdom of Serbia with the State of Slovenes, Croats and Serbs to form the Kingdom of Serbs, Croats and Slovenes.