Yaroslav, Battle of

Yaroslav, Battle of. A clash between the army of the Galician-Volhynian prince, Danylo Romanovych, and Hungarian-Polish forces near Yaroslav (now Jarosław), Galicia, on 17 August 1245. Hungary and Poland took advantage of the weakened condition of the Principality of Galicia-Volhynia after the Tatar invasion of 1241 to seize Ukrainian territories. They exploited the hostility of Galician boyars toward Prince Danylo Romanovych and invaded Galicia, led by the expelled prince of Chernihiv, Rostyslav Mykhailovych (son-in-law of the Hungarian king, Béla IV). In the summer of 1245 Béla joined with Polish forces and Galician boyars under Rostyslav Mykhailovych's command and besieged Yaroslav. Danylo Romanovych's army, along with a detachment of Cumans, set out from Kholm to defend Yaroslav, and proved victorious in a battle on the Sian River. The Hungarian voivode Fila was slain, and the boyar leader Volodyslav was taken prisoner and later executed. Danylo's definitive victory quelled Polish and Hungarian aggression and boyar rebellions. It also enabled Danylo to strengthen his authority and to raise the principality's prestige.