Boleslaus III is restored to authority with armed support from Bolesław I the Brave of Poland.

Boleslaus III, called the Red or the Blind, a member of the Přemyslid dynasty, was Duke of Bohemia from 999 until 1002 and briefly again during the year 1003. During his chaotic reign, Bohemia became a pawn in the long German–Polish War between King Henry II and Duke Bolesław I, "the Brave", of Poland.

Bolesław I the Brave, less often known as Bolesław the Great, was Duke of Poland from 992 to 1025 and the first King of Poland in 1025. He was also Duke of Bohemia between 1003 and 1004 as Boleslaus IV. A member of the Piast dynasty, Bolesław was a capable monarch and a strong mediator in Central European affairs. He continued to proselytise Western Christianity among his subjects and raised Poland to the rank of a kingdom, thus becoming the first Polish ruler to hold the title of rex, Latin for king.

Greater Poland, often known by its Polish name Wielkopolska, is a Polish historical region of west-central Poland. Its chief and largest city is Poznań followed by Kalisz, the oldest city in Poland.