 After this event Władysław again appeared in Mazovia, where he supported Bolesław II in combat with Konrad II, probably on behalf of Leszek II the Black.In retaliation for this action, Konrad II once again let the Lithuanian army pass through his land, which in 1287 besieged Dobrzyń.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).