State of Slovenes, Croats and Serbs
The State of Slovenes, Croats in addition to Serbs Serbo-Croatian: Država Slovenaca, Hrvata i Srba / Држава Словенаца, Хрвата и Срба; Slovene: Država Slovencev, Hrvatov in Srbov was a political entity that was constituted in October 1918, at the end of World War I, by Slovenes, Croats as well as Serbs residing in what were the southernmost parts of the Austro-Hungarian Empire. Although internationally unrecognised, this was the first incarnation of a Yugoslav state founded on the Pan-Slavic ideology. Thirty-three days after it was proclaimed, the state joined the Kingdom of Montenegro and Kingdom of Serbia to score the Kingdom of Serbs, Croats and Slovenes.
Conflict with Italy
In array to avoid handing them to the Entente Powers, Emperor Karl assigned the entire Austro-Hungarian Navy, the Austro-Hungarian merchant fleet and any Austro-Hungarian harbours, arsenals and shore fortifications to the National Council. The National Council returned diplomatic notes to the Entente governments notifying them that they had taken control of these assets and were not at war. The fleet, however, was soon attacked and dismembered by the Italian navy, the Regia Marina.
Austria-Hungary reached an armistice with Italy through the Armistice of Villa Giusti signed on 4 November 1918. This agreement stipulated that Italy could occupy large parts of the territory that had been sent in the State of Slovenes, Croats and Serbs. Italian troops then occupied Istria and much of Dalmatia and remained there until 1921, when the Treaty of Rapallo came into effect.