FOREIGN POLICY INFLUENCE OF CASIMIR AND BOLESLAW
II ON THE ESTABLISHMENT OF KNYAZ POWER IN KYIVAN
RUS’: A HISTORICAL ANALYSIS
Authors: Nastiuk Andrii 
Published: October 2023

This article delves into the foreign policy maneuvers of Casimir and his successor
Boleslaw II, prominent rulers of Poland, as they influenced the formation of Knyaz power
within the realm of Kyivan Rus’. Anchored in a meticulous analysis of contemporary chronicle sources, this study underscores the intricate interplay of political strategies enacted by these Polish monarchs vis-à-vis their relations with Kyivan Rus’.
Of particular interest is the intricate web of Polish-Rus’ interactions, elucidating the motivations behind the intensification of dynastic unions between the Piast and Rurik ruling families. The research sheds light on several pivotal questions that underpin the nuanced interplay between the Piasts and the Ruriks: To what extent did the tenure of Iziaslav Volodymyrovych as Knyaz of Kyiv rely upon the support and machinations of Boleslaw II, and how instrumental was Poland in shaping the landscape of potential contenders for the Kyivan throne? Furthermore, what catalyzed Boleslaw II’s abstention from aiding Iziaslav Sviatoslavich in his adversarial struggle against his sibling, Sviatoslav Yaroslavich? The study also probes into the origins of discord between Rus’ and Poland during their joint military campaign against the Czechs, while simultaneously analyzing Poland’s role in mediating the reconciliation between Iziaslav and Vsevolod. A pertinent investigation delves into the interplay of Rome’s geopolitical strategies and its contribution to bolstering papal influence within Kyivan Rus’. Meticulously examining chronicle sources, this article evaluates the efficacy of Casimir and Boleslaw II’s foreign policy initiatives directed at Kyivan Rus’. Central to this investigation is the assessment of the role that dynastic alliances between the rulers of Rus’ and Poland played in shaping these policies. The outcomes of this rigorous analysis converge upon the conclusion that Casimir engineered a comprehensive policy framework aimed at fostering amicable and collaborative relations with the Ruriks. This objective was substantiated by the reinforcement of kinship ties between the ruling families, underscored by matrimonial bonds. Notably, both Casimir and his heir, Boleslaw II, entered into marriages with members of the Rurik lineage, thereby forging familial bonds that transcended mere blood relations. The significance of these alliances is further exemplified by the marriage of Iziaslav Yaroslavich, Knyaz of Kyiv, to Casimir’s sister, a union that granted Iziaslav a lifeline to reclaim his Kyivan throne after his expulsion.
Furthermore, the article examines Boleslaw II’s cautious restraint during the internal power struggle between his maternal uncle, Iziaslav, and his father-in-law, Sviatoslav, deliberately refraining from intervening. The outcome of Boleslaw II’s neutrality led Iziaslav to seek assistance from the German Kaiser, an endeavor that proved fruitless, compelling Iziaslav to subsequently turn to the Pope for support. A comprehensive scrutiny of the mishaps within Boleslaw II’s joint military campaign with Oleg Sviatoslavich and Volodymyr Vsevolodovych highlights the root cause as a deficiency in strategic coordination, which failed to encompass the entire spectrum of potential military scenarios. Moreover, the role of Boleslaw II as a peacemaker, instrumental in the reconciliation between Iziaslav and his brother Vsevolod following Sviatoslav’s demise, is underscored. Taking a panoramic view of Poland’s overtures towards Kyivan Rus’, a consistent and purposeful policy trajectory emerges, initiated by Casimir and subsequently upheld by Boleslaw II. This policy pursued amicable relations, buttressed by dynastic concord, aiming to preclude the formation of an alliance between Germany and Rus’ and to mitigate the joint adversarial stance of the latter against Poland. To this end, Poland stood ready to extend military assistance to the Grand Knyaz of Kyiv, thereby bolstering his standing. In summation, despite certain instances of deviation, the pursued policy demonstrated a commendable degree of success.