Casimir II the Just

Casimir II the Just (Polish: Kazimierz II Sprawiedliwy; 28 October 1138 – 5 May 1194) was Duke of Wiślica in Lesser Poland from 1166 to 1173, and Duke of Sandomierz from 1173 onward. In 1177, he became ruler of the Polish Seniorate Province at Kraków and thereby High Duke of Poland — a position he held until his death, though briefly interrupted by his elder brother and predecessor, Mieszko III.

Born after his father’s death, Casimir was initially excluded from territorial inheritance. Casimir’s rise to power came amid widespread dissatisfaction with the rule of his elder brother, Mieszko III the Old. In 1177, with the support of influential nobles and church leaders, Casimir assumed control of Kraków and thereby the seniorate, becoming High Duke of Poland. His reign was marked by a conciliatory and pragmatic approach to governance. Notably, at the Assembly of Łęczyca in 1180, Casimir granted significant privileges to the Church, limiting ducal authority over ecclesiastical property and succession. This act strengthened his domestic support and earned him a reputation as a ruler who governed through consensus rather than coercion, initiating an early form of parliament.

As High Duke, Casimir II worked to stabilize internal politics while navigating the persistent rivalries among Piast princes. He maintained relative peace within his domains, engaged diplomatically with surrounding states, and sought to reinforce the position of his own line within the dynasty. In 1186, Casimir also inherited the Duchy of Masovia from his nephew Leszek, becoming the progenitor of the Masovian branch of the royal Piast dynasty and great-grandfather of the later Polish king Ladislaus the Short. Casimir II died in 1194, leaving behind a legacy of moderation that distinguished him among the often turbulent dukes of divided medieval Poland. The honorific title "the Just" was not contemporary and first appeared in the 16th century.