Borna was the Duke of Croatia from to 821 and vassal of the Frankish Empire. He resided in Nin and was the ruler of most of the Croats in northern Dalmatia. Borna's predecessor was Višeslav of Croatia, probably his father. After his death in 821, he was succeeded by his nephew Vladislav. He is mentioned in the Royal Frankish Annals (Annales regni Francorum) in entries regarding 818–821. His titles were "Duke of the Guduscani" (a Croatian tribe from Lika and northern Dalmatia) in 818; "Duke of Dalmatia" in 819; "Duke of Dalmatia and Liburnia" in 821. Historiography treats him as a ruler of Dalmatian Croatia. History Borna is documented in the "Royal Frankish Annals" (Annales regni Francorum). He is first mentioned regarding an 818 meeting at Herstal of Frankish Emperor Louis the Pious with envoys of the Obotrites, Borna (duke of the Guduscani), and of the Timociani, who had recently revolted against the Bulgars and switched sides to the Franks, and also Ljudevit, duke of the Slavs in Lower Pannonia, the commander of the March of Friuli. Historiography predominantly treats the Guduscani as a tribe in Lika, along the river Gacka. In July 819, another Frankish assembly was held at Ingelheim, and because of Ljudevit's rebellion against the Franks, Frankish troops were sent from Italy to Pannonia, but returned without accomplishment. Ljudevit sent envoys to the Franks with conditions that were not accepted by the Frankish emperor; Ljudevit continued the rebellion and sent envoys to neighbouring tribes to join him, managing to win over the Timociani who had initially submitted to the Franks. A small Frankish army clashed with Ljudevit's army in Carinthia, destroyed much of it and drove it out. Borna, now the "Duke of Dalmatia", with a large army met Ljudevit's advancing army on the Kupa river. The Guduscani deserted Borna at the first encounter, but he fled safely with his bodyguard. During this battle, Dragomuž (Dragomosus), Ljudevit's father-in-law who had joined Borna with the outbreak of the rebellion, fell. Borna conquered the Guduscani again after they had returned home. In December, Ljudevit used the opportunity to attack Dalmatia with a large army, ravaging the country. Borna attacked Ljudevit with crack troops, after storing as much as he could in his castles, seeing that he was no match for him. Worn down, attacked in the rear and flank, with heavy losses, Ljudevit was forced to retreat from Borna's