Leszek II the Black
On 30 September 1288, Leszek II the Black, Duke of Krakow and Sieradz, died without issue, thus transferring power in the principality of Sieradz to his eldest half-brother, Władysław I Łokietek (his full brother Ziemomysł had already died in 1287). While Władysław now ruled over Brześć Kujawski and Sieradz, Casimir II inherited the duchy of Łęczyca, and Siemowit assumed control of the land of Dobrzyń.