Serbian Uprising Against Byzantine RuleKotor, Montenegro
In 1149, Beloš's Hungarian army aided Uroš II against the Byzantines. The Serbs under brothers Uroš II and Desa revolted against the Byzantines, when Manuel was in Avlona planning an offensive across the Adriatic, and this revolt posed danger to the Emperor if he would attack Italy, as the Serbs could strike at the Adriatic bases.
Uroš II and Desa next undertook an offensive against Radoslav of Duklja, who was a loyal Byzantine vassal. Radoslav was pushed to the southwestern corner of Duklja, to Kotor, and retained only the coastal area, with the brothers holding much of inland Duklja and Trebinje – over two thirds of Duklja. Radoslav sought help from the Emperor, who sent aid from Dyrrhachium. At this moment, the Chronicle of the Priest of Duklja ends, presumably because the author of the original text had died. A major war was about to erupt in the Balkans; Uroš II and Desa, in light of Byzantine retaliation, sought aid from their brother Beloš, the count palatine of Hungary. By 1150, Hungarian troops played an active role in Serbia.