|Duke of Kuyavia|
Coat-of-arms of Piast of Poland
|Died||13 September 1195|
|Noble family||Piast dynasty|
|Spouse(s)||Dobroslawa of Pomerania|
|Father||Mieszko III the Old|
|Mother||Eudoxia of Kiev|
Almost immediately after his birth, Boles?aw was considered the main successor to his father in the Greater Poland inheritance, especially since Mieszko III had become the High Duke and overlord of Poland in 1173 after the death of his brother Boles?aw IV the Curly.
In 1177 the authoritarian government of Mieszko III began The Rebellion of The Kraków Nobility and called upon his brother, Casimir II the Just to take the title of High Duke. At the same time was joined to the conspiracy Mieszko III's eldest son Odon (from his first marriage), who resented his father's favoritism for the children born to his second marriage with Eudoxia. The revolt which broke out in Greater Poland between 1177-1179 was a complete surprise to Mieszko III, who was forced to escape from Poland with Boles?aw and his younger brothers Mieszko and W?adys?aw. The deposed High Duke took refuge in Bohemia, Germany and then in the court of his son-in-law Bogislaw I, Duke of Pomerania.
Mieszko III regained the control over Greater Poland in 1181, thanks to the help of Pomeranian troops. One he recovered his domains, Mieszko III didn't divided his domains between his sons (as was expected) and already trying to pull his own political plans who were centered in the recovery of Kraków and with this, the Seniorate Province.
In 1186 Leszek, Duke of Masovia died without issue. In his will, he left all the Masovian-Kuyavian principality to his youngest uncle Casimir II the Just. However, Mieszko III could mastered Kuyavia; soon after, he passed his new acquisition to Boles?aw (some historians believed that Boles?aw only obtain Kuyavia in 1194 after the death of Casimir II the Just).
Another important year in Boles?aw could be 1191, when his father, using the absence of Casimir II the Just (who was involved in the Kievan Rus' succession disputes) seized and conquer Kraków. Then, for unknown reasons, Mieszko III didn't took personally the government of the capital, but gave them to Boles?aw (although some sources believed that the prince who was appointed Governor of Kraków was Mieszko the Younger). Boles?aw's rule as governor in Kraków wasn't too long, because soon Casimir II the Just could recover his authority over the capital and imprisoned his nephew. However, the victorious Casimir II acted generously and sent the prince with his father.
On 5 May 1194 Casimir II the Just died unexpectedly, leaving to minor sons: Leszek and Konrad. Mieszko III saw his brother's death as a new opportunity to regain the supreme power; however, this time the local nobility stood at the side of Casimir II's sons.
Mieszko III's Greater Poland and Kuyavian troops and the Lesser Poland's troops (who fight on behalf of Leszek and Konrad), led by the voivode Miko?aj Gryfita, faced in the bloody Battle of Mozgawa (13 September 1195); Boles?aw was among the casualties. Mieszko III, seriously injured, withdraw to Kalisz without waiting for the Silesia troops who came to his aid, led by Mieszko I Tanglefoot and Jaros?aw of Opole.
Around 1187/89, Boles?aw married with Dobroslawa (b. 1162/72 - d. 23 November 1206/after 1230?), a Pomeranian princess. They all certainly had only female offspring, but the exact number remains disputed. Various sources show some of the following three daughters, but no source shows all three of them:
After his death without male issue, Kuyavia returned to his father Mieszko III, but in 1198 he ceded the Duchy to Casimir II's sons in exchange of his recognition as High Duke.