According to Stephen A. Hart, author of "Partisans: War in the Balkans 1941–1945", the ethnically mixed region of Dalmatia held close and amicable relations between the Croats and Serbs who lived there in the late 19th and early 20th centuries. Many early proponents of a united Yugoslavia came from this region, such as Ante Trumbić, a Croat from Dalmatia. However, by the time of the outbreak of the Yugoslav Wars, any hospitable relations between Croats and Serbs in Dalmatia had broken down, with Dalmatian Serbs fighting on the side of the self-declared proto-state Republic of Serbian Krajina.