From the beginning of his sole rule, Bolesław established contacts with the Margraviate of Brandenburg, ruled by the House of Ascania; in this, he followed the policy of his brother Przemysł I, who even betrothed his eldest daughter Constance with Conrad, son of Margrave John I. Three years after Przemysł I's death (in 1260), Constance and Conrad were formally married. As a dowry, Brandenburg received the castellany of Santok (but without the important main city) with the consent of a "wiec" reunited in Greater Poland, which took place on 1 July 1260 in Poznań.