In the first half of the 13th century Silesian duke Henry I the Bearded, reunited much of the divided Kingdom of Poland ("Regnum Poloniae"). His expeditions led him as far north as the Duchy of Pomerania, where for a short time he held some of its southern areas. He became the duke of Cracow (Polonia Minor) in 1232, which gave him the title of senior duke of Poland (see Testament of Bolesław III Krzywousty), and came into possession of most of Greater Poland in 1234. Henry failed in his attempt to achieve the Polish crown. His activity in this field was continued by his son and successor Henry II the Pious, until his sudden death in 1241 (Battle of Legnica). His successors were not able to maintain their holdings outside of Silesia, which were lost to other Piast dukes. Polish historians refer to territories acquired by Silesian dukes in this period as "Monarchia Henryków śląskich" ("The monarchy of the Silesian Henries"). In those days Wrocław was the political center of the divided Kingdom of Poland.