The Hungarian Civil War of 1264–1265 (Hungarian: 1264–1265. évi magyar belháború) was a brief dynastic conflict between King Béla IV of Hungary and his son Duke Stephen at the turn of 1264 into 1265. Béla's relationship with his oldest son and heir, Stephen, became tense in the early 1260s, because the elderly king favored his daughter Anna and his youngest child, Béla, Duke of Slavonia. Stephen accused Béla of planning to disinherit him. After a brief skirmish, Stephen forced his father to cede all the Kingdom of Hungary's lands east of the Danube to him and adopted the title of junior king in 1262. Nevertheless, their relationship remained tense, causing a civil war by the end of 1264. The conflict resulted in Stephen's victory over his father's royal army. They concluded a peace treaty