Yaroslav Osmomysl [Ярослав Осьмомисл; Jaroslav], b ?, d 1 October 1187 in princely Halych. Galician prince; son of Volodymyrko Volodarovych. He is first mentioned in the chronicles under the year 1150, when he married Olha, the daughter of Yurii Dolgorukii. In Slovo o polku Ihorevi (The Tale of Ihor's Campaign) Yaroslav is given the appellation Osmomysl (possessed of eight senses, ie, wise and perceptive). Upon his assumption of the throne in 1153, Halych principality was in conflict with Kyiv principality and a number of Volhynian cities. Yaroslav Osmomysl was ready to accept the primacy of Iziaslav Mstyslavych of Kyiv, but the Galician boyars were opposed. Iziaslav Mstyslavych launched a campaign against the Galicians and defeated them at Terebovlia, on the Seret River.
Iziaslav Mstyslavych's death in 1154 ushered in a period of peace between Kyiv and Galicia, apart from the tenure of Iziaslav III Davydovych (1158–61), whom Yaroslav Osmomysl defeated with the assistance of Mstyslav Iziaslavych in 1159. That year Yaroslav Osmomysl also fought against his cousin, Ivan Rostyslavych Berladnyk, who made an unsuccessful attempt from the Danube River lowlands to conquer Galicia. Yaroslav Osmomysl maintained good relations with Yurii Dolgorukii and participated in campaigns against the Cumans (about which an account is given in Slovo o polku Ihorevi). He also lived in relative harmony with his neighbors in Poland and Hungary, the Byzantine emperor, and Frederick I Barbarossa. Yaroslav Osmomysl did not interfere in the conflict between Byzantium and Hungary, but after he harbored his relative, Andronicus I Comnenus (cousin of the Byzantine emperor, Manuel I), in 1164, his relations with Constantinople soured. In 1174 he supported Yaroslav Iziaslavych's ascent to the Kyivan throne.
Yaroslav Osmomysl expanded his principality by annexing the territories between the Dnister River and the Carpathian Mountains and the Danube River lowlands. His large standing army made him one of the mightiest princes of Kyivan Rus’. Many Galician cities were built up and fortified during his reign. In 1153–7 the Dormition Cathedral was built in princely Halych.
The Galician boyars initially aided Yaroslav Osmomysl, particularly in his war with Iziaslav Mstyslavych, but as they grew richer through trade, they transformed themselves into a hereditary aristocracy and began interfering in Yaroslav Osmomysl's state and personal affairs. In 1172 he left his wife, Olha, and took a boyar's daughter, Nastasiia, as his mistress. The boyars rebelled and forced him to reinstate Olha, and had Nastasiia burned as a witch. Olha withdrew to a convent in Suzdal and died in 1182. Yaroslav Osmomysl's last wishes were to grant Oleh Yaroslavych (Nastasiia's son) the rule of princely Halych, and Peremyshl to Volodymyr Yaroslavych, Olha's son, but the boyars expelled Oleh Yaroslavych after Yaroslav Osmomysl died.
In 1937 Yaroslav Pasternak unearthed the sepulcher of a notable man during the archeological excavation of the Dormition Cathedral of the princely Halych (now Krylos). His expectation that the sepulcher contained the mortal remains of Yaroslav Osmomysl was confirmed by S. Horbenko in 1996.
Pasternak, Ia. ‘Sarkofah Iaroslava Osmomysla,’ in Staryi Halych (Cracow–Lviv 1944)
Hrytsak, P. Halyts’ko-Volyns’ka derzhava (New York 1958)
Horbenko, S. Iaroslav Os'momysl: rekonstruktsiia antropolohichna i istorychna (Lviv 1996)
[This article was updated in 2010.]