who, still dissatisfied with the 1172 partition, annexed the Opole territory of late Jarosław. The Duchy of Opole remained with the estates of Mieszko's descendants, whereby the secession of Upper Silesia was conclusive. In 1206 Henry I came to an agreement with the Polish High Duke Władysław III Spindleshanks to swap Lubusz Land for the Greater Polish Kalisz region. The plan however was foiled, when Władysław III lost the seniorate and furthermore Lubusz was occupied by the troops of the Wettin margrave Conrad II of Lusatia. Duke Henry had to struggle for his northwestern outpost, which he regained upon the margrave's death in 1210. He had to defend Lubusz once more against the campaigns of Landgrave Louis IV of Thuringia from 1221. Upon the death of his cousin Duke Casimir I of Opole, son of Mieszko I Tanglefoot, in 1230, he acted as guardian of his minor nephews, thereby once again ruling over whole Silesia. In 1232 he became High Duke of Poland, and as he was able to secure the succession of his son Henry II the Pious upon his death in 1238, it seemed that the Polish fragmentation could be overcome and the will of Bolesław III Krzywousty would finally be fulfilled. Henry II in 1239 had to resign the regency of Upper Silesia in favour of his cousin Mieszko II the Fat. He anew defended Lubusz, this time against the forces of the Ascanian margraves of Brandenburg, and in 1241 granted it to his second son Mieszko. The hopes for a re-unification of the Polish lands under the Silesian Piasts ended with the Mongol invasion of Poland and Henry's death at the 1241 Battle of Legnica. His eldest son Bolesław II the Bald could not prevail as High Duke against Bolesław V the Chaste of Lesser Poland and, after he regained Lubusz upon the death of his brother Mieszko in 1242, finally had to divide his Silesian heritage with his younger brothers in 1248: Bolesław II himself took his residence in the west at Legnica, thereby establishing the Duchy of Legnica together with his youngest brother Konrad. Soon after he sold Lubusz to the Brandenburg margraves, who finally gained a foothold beyond the Oder to establish the Neumark region. In 1251 Konrad, actually elected Bishop of Passau, forced Bolesław to cede the Duchy of Głogów to him. The residence of Wrocław fell to his younger brothers Henry