In 1247 Przemysł I was forced by the local knights to give his brother Bolesław the district of Kalisz as a separated Duchy, but in foreign policy he retained full authority over Greater Poland.Chronicle of Greater Poland, pp. 227–228. See Stanisław Zachorowski, Wiek XIII i panowanie Władysława Łokietka; Roman Grodecki, Stanisław Zachorowski, Jan Dąbrowski, Dzieje Polski Średniowiecznej w dwu tomach, Second Edition, Kraków 1995, p. 296; Gerard Labuda, Dzieje Wielkopolski, vol. I, p. 294; Bronisław Nowacki, Przemysł II 1257–1296. Odnowiciel korony Polskiej, Poznań 1997, p. 18, where the authors consider that the separation of Kalisz districtas an independent Duchy was due to powerful intervention of the local nobility. In turn, Aleksander Swieżawski, Przemysł król Polski, Warsaw 2006, p. 37, considers that the idea of give a separated district to Bolesław was fully voluntary, since none of the primary sources informed about pressures from the nobility. It was not the final division. A year later, the ruler of Greater Poland crushed the opposition by imprisoning its leaders, the Castellan of Poznań Thomas of Nałęczów and his sons. Przemysł I released them in 1250, when he was involved in the conflict between Bolesław II the Bald and his brother Konrad (husband of Przemysł I's sister Salomea). The intervention of the Greater Poland Duke helped Konrad to obtain the district of Głogów as his own independent Duchy.Chronicle of Greater Poland, pp. 234–236.
