In 1273, after the victorious expedition against Brandenburg, Przemysł II began to claim his own separated Duchy. Unable to face the powerful pressure, Bolesław agreed to this and given his nephew the district of Poznań. To bind Przemysł II with his politics, Bolesław arranged the marriage of his nephew with Ludgarda, daughter of Henry I the Pilgrim, Lord of Mecklenburg. In addition, Ludgarda was a granddaughter of Duke Barnim I of Pomerania, and thanks to this union the alliance with Western Pomerania was reinforced. Dukes of Greater Poland political path, however, soon spread, as Przemysł II became involved with Henry IV Probus, and Bolesław, using the imprisonment of Henry IV in 1277, tried to force financial concessions. Bolesław supported this policy with the marriage of his firstborn daughter Elisabeth with Henry V the Fat, Duke of Legnica.