Boleslaw I the Brave (Polish: Boleslaw I Chrobry (Chrobry means the valiant in Polish) (966 or 967 - June 17, 1025), of the Piast Dynasty — son of Mieszko I and of his first wife, the Czech princess Dobrawa — ruled as Duke of Poland, 992-1025, and as King of Poland in 1025.

Boleslaw's career
In 984 Boleslaw married Rikdaga, daughter of Riddag (Rikdag, Ricdag), margrave of Meissen. Subsequently he married Judith, daughter of Geza, Grand Duke of Hungary; then Enmilda, daughter of Dobromir, Duke of Lusatia; and lastly Oda, daughter of the margrave of Meissen. His wives bore him sons, including Bezprym, Mieszko II and Otton; and a daughter, Mathilde. After his father's death around 992, Boleslaw was able to expel his father's second wife, Oda, and her sons, and unite the country again.

In 997 Boleslaw sent Saint Adalbert of Prague to Prussia, on the Baltic Sea, on a mission to convert the heathen Prussians to Christianity — an attempt that would end in Adalbert's martyrdom and subsequent canonization.

By this time, Boleslaw already possessed Silesia and Pomerania (with its chief city, Gdansk) and Lesser Poland (with its chief city, Kraków). In 999 Boleslaw annexed present-day Moravia, and in 1000 or 1001, parts of present-day Slovakia.

In A.D. 1000, Holy Roman Emperor Otto III, while on pilgrimage to the tomb of St. Adalbert at Gniezno, invested Boleslaw with the title Frater et Cooperator Imperii ("Brother and Partner in the Empire"). Some historians state that the Emperor also pledged a royal crown to Boleslaw. During that same visit, Otto III accepted Gniezno's status as an archbishopric (see Congress of Gniezno).
After the untimely death of Otto III at age 22 in 1002, Boleslaw conquered Meissen and Lusatia, wresting imperial territory for himself during the disputes over succession to the Imperial throne. He and his father had earlier backed Henry the Wrangler against Otto, and Boleslaw now accepted the accession, as Emperor, of Henry II, son of the earlier Henry.

Boleslaw conquered, and made himself Duke of, Bohemia and Moravia in 1003 - 1004, ruling as Boleslav IV.

At the request of his son-in-law Sviatopolk I of Kiev, the Polish King intervened in Kievan affairs: not only did he expel Yaroslav the Wise from Kiev, but he deployed his troops in Rus' capital for about half a year, until they were driven out by a popular rising. It was during this campaign that Boleslaw annexed the Red Strongholds, later called Red Ruthenia.

The intermittent wars with Germany ended with the Peace of Bautzen (Budziszyn) in 1018, which left Sorbian Meissen and Lusatia in Polish hands.

Emperor Henry II obliged Boleslaw to pledge his fealty again in exchange for the lands that he held in fief. After Henry's death in 1024, Boleslaw crowned himself king (1025), thus raising Poland to the rank of a kingdom.

Boleslaw sent an army to aid his friend — more probably, nephew — Canute in his conquest of England.

Boleslaw's son, Mieszko II, crowned himself king immediately upon his father's death.

Significance of Boleslaw's reign in Polish history
Boleslaw was the first Polish king, since it was during his reign that Poland became a kingdom, despite the fact that some Polish rulers before 1295 would never receive a crown. He was the first Polish ruler baptised at birth, the first real Christian ruler of Poland. He founded the independent Polish province of the Church and made Poland a strong power in Europe. Boleslaw for the first time unified all the provinces that subsequently came to comprise the traditional territory of Poland: Greater Poland, Lesser Poland, Masovia, Silesia, and Pomerania.

He was a national hero to the Sorbs of Lusatia.