State of Slovenes, Croats and Serbs, 1918
On 29 October 1918, the Croatian Parliament (Sabor) declared independence and joined the Slovenes and other Slavs in Bosnia and Herzegovina, in the southernmost parts of Austria–Hungary. They proclaimed the State of Slovenes, Croats and Serbs, declaring that their ultimate intention was to unite with Serbia and Montenegro in a large South Slav state. Their flag remained the red-white-blue tricolour, although the proportions may have differed.