Casimir II the Just (1138 - 5 May 1194; Polish: Kazimierz II Sprawiedliwy) of the Piast dynasty was the youngest son of Boleslaus III of Poland. He reigned as duke of Kraków and senior prince of Poland (see Seniorate ) from 1177 until his death. Born shortly before or after his father's death, and omitted (possibly for that reason) from Boleslaus's will dividing the kingdom between Casimir's four elder brothers, he set about securing the territorial basis for a claim to power, gaining the dukedom of Wislica in 1167 and of Sandomierz in 1173. In 1180 he won acceptance by the nobility and clergy of the principle of hereditary succession to the Kraków dukedom, though it would take more than a century to restore the Polish kingship.
born post-mortem.
