Adam Naruszewicz wrote that Danylo Ostrozky was starost of Przemyśl, officer of Casimir III the Great when he inherited Galicia after the death of Boleslaw-Yuri II of Galicia. Daniel was probably only temporary supporting King Casimir, because in 1344 he called the Tatars to fight for Galicia in the Galicia–Volhynia Wars, like Dmytro Dedko who died in the same year. Finally Prince Danylo allied to Liubartas who also rivaled for Galicia with Tatars, Poles and Hungarians. He received Ostroh from Liubartas, King of Galicia–Volhynia, where he rebuilt the castle destroyed by the Tatars.