Complex sentence: The apparent barrenness of the Duchess encouraged Zbigniew's expectations of succeeded his father despite his illegitimacy; but in 1085 the Barons forced Duke Władysław I to recall Mieszko Bolesławowic (only son of the deposed Bolesław II) from his exile in Hungary.
Split into simpler sentences: The apparent barrenness of the Duchess encouraged Zbigniew's expectations to succeeded his father despite his illegitimacy. However in 1085, likely due to the pressure of the barons, Duke Władysław I recalled Mieszko Bolesławowic the only son of the deposed Bolesław II from his exile in Hungary.