Casimir I the Restorer
The separation of Pomerania during the reign of Casimir I the Restorer contributed to the weakening of the Polish state, and subsequent rulers during the second half of the 11th century weren't able to unite all the lands that once belonged to Mieszko I and Bolesław I the Brave. All attempts made to reconquer this area failed. Only after defeating Zbigniew and repelling the claims of Bohemia against Silesia in 1109, Bolesław III Wrymouth was able to direct the expansion to the West, which he intended to return to Poland.