Medieval coin of King Bela III of Hungary 1172-1196 AD

Béla III (Hungarian: III. Béla, Croatian: Bela III., Slovak: Belo III.; c. 1148 – 23 April 1196) was King of Hungary and Croatia between 1172 and 1196. He was the second son of King Géza II and Géza's wife, Euphrosyne of Kiev. Around 1161, Géza granted Béla a duchy, which included Croatia, central Dalmatia and possibly Sirmium. In accordance with a peace treaty between his elder brother, Stephen III, who succeeded their father in 1162, and the Byzantine Emperor Manuel I Komnenos, Béla moved to Constantinople in 1163. He was renamed to Alexios, and the emperor granted him the newly created senior court title of despotes. He was betrothed to the Emperor's daughter, Maria. Béla's patrimony caused armed conflicts between the Byzantine Empire and the Kingdom of Hungary between 1164 and 1167, because Stephen III attempted to hinder the Byzantines from taking control of Croatia, Dalmatia and Sirmium. Béla-Alexios, who was designated as Emperor Manuel's heir in 1165, took part in three Byzantine campaigns against Hungary. His betrothal to the emperor's daughter was dissolved after her brother, Alexios, was born in 1169. The emperor deprived Béla of his high title, granting him the inferior rank of kaisar.