In preparation for the peace conference that was expected to follow World War I, in the spring of 1917 the British Foreign Office established a special section responsible for preparing background information for use by British delegates to the conference. Croatia-Slavonia and Fiume is Number 8 in a series of more than 160 studies produced by the section, most of which were published after the conclusion of the 1919 Paris Peace Conference. Until the end of World War I, Croatia-Slavonia and Fiume were part of the Austro-Hungarian Empire and provided Hungary with its main outlet to the sea. The appendix contains excerpts from the Nagoda (Agreement), the document adopted in 1868 that defined the complex constitutional arrangements between Hungary, Croatia-Slavonia (Hungarian territory historically included in the Lands of the Crown of Saint Stephen), and Dalmatia (an Austrian crown land). Together these lands formed a “triple kingdom.” Fiume (present-day Rijeka, Croatia), an important port once part of Charlemagne’s empire, was attached directly to Hungary. These territories all became part of the newly established Kingdom of Serbs, Croats, and Slovenes (Yugoslavia from 1929) after World War I, but Fiume was ceded to Italy in 1924. Today all are part of the Republic of Croatia. The book includes sections on physical and political geography, political history, social and political conditions, and economic conditions. The study notes the economic importance of the port of Fiume and the railroad lines linking it to the interior of the empire. A note on place-names in Croatia-Slavonia gives the names of important towns in Croatian, Magyar (Hungarian), German, and Italian.