Casimir is the only Polish king who both received and kept the title of the Great in Polish history ( Bolesław I Chrobry is also called the Great, but his title Chrobry ( Valiant ) is now more common ).

This view is based on the fact that Thietmar of Merseburg in his chronicles named Gunzelin, Gunther's son, brother of Bolesław I the Brave, Dobrawa's son.

Currently, historians believed that Gunzelin and Bolesław I are in fact cousins or brothers-in-law.

# Bolesław I the Brave ( Chrobry ) ( b. 967-d. 17 June 1025 ).

Also, it is unclear why the document does not mention Mieszko's eldest son, Bolesław I the Brave.

Attempts to conquer Prussian land began in 997, when Bolesław I Chrobry, at the urging of the Pope, sent a contingent of soldiers and a missionary ( Adalbert of Prague ) to the pagan Prussians on a crusade of conquest and conversion.

Dark pink area represents Poland at end of rule of Mieszko I of Poland | Mieszko I ( 992 ); light pink area added ( northwest lost ) during reign of Bolesław I the Brave | Bolesław I ( died 1025 ).

Mieszko's son Bolesław I Chrobry established a Polish Church province, pursued territorial conquests and was officially crowned in 1025, becoming the first King of Poland.

This was followed by a collapse of the monarchy and restoration under Casimir I. Casimir's son Bolesław II the Bold became fatally involved in a conflict with the ecclesiastical authority, and was expelled from the country.

At the age of twelve, Hedwig married Henry I the Bearded, son and heir of the Piast duke Bolesław I the Tall of Silesia.

He was the second son of Bolesław I the Brave, but the eldest born from his third wife Emmilda, daughter of Dobromir, possible ruler of Lusatia.

It is thought that the choice of this name for his son was an expression of warming relations between Bolesław I and his stepmother Oda.

Since Mieszko II was politically active before his father's death, Bolesław I the Brave appointed him as his successor.

A few months later Bolesław I the Brave paid homage in person.

Another hypothesis assumes that the territories were transferred by Bolesław I to him, and as a result made Mieszko a vassal of the Empire.

Probably after the wedding, and in accordance with prevailing custom, Bolesław I gave a separate district to Mieszko II to rule: Kraków.

He was released only after the intervention of the Emperor, who, despite the planned betrayal of Bolesław I, loyally acted on behalf of his vassal.

In the absence of Sieciech and Bolesław, who were captured by Hungarians and kept captive, Prince Władysław I then undertook a penal expedition to Silesia, which was unsuccessful and subsequently obliged him to recognize Zbigniew as a legitimate heir.

Bolesław subsequently accompanied Otto III on his way back to Germany.

The Duchy of Silesia, one of the hereditary provinces of Poland, Silesia, was granted to Bolesław III's eldest son, Władysław II the Exile, and was subsequently divided among his sons Bolesław I the Tall ( Wrocław / Lower Silesia ), Mieszko I Tanglefoot ( Racibórz / Upper Silesia ) and Konrad Spindleshanks ( Głogów ).

In 1003, he rebelled against his elder brother Boleslaus III, who had him emasculated, but was unable to secure the throne, which was subsequently taken by Bolesław the Brave, King of Poland.

Gallus was a foreign monk who accompanied King Bolesław III Wrymouth in his return from Hungary to Poland.

Before World War II, French historian Pierre David advanced a theory that Gallus might have been a Hungarian monk from Saint Giles ' Monastery in Somogyvár who accompanied King Bolesław III in his return from Hungary to Poland.

Bolesław accompanied him.

The congress was organized by Polish king Bolesław Chrobry and Holy Roman Emperor Otto III, and also led to the establishment of bishoprics in Kraków and Wrocław, connecting the territories of the Polish state.

Bezprym had, however, always been disliked by his father, as indicated by his name ( the Piasts tended to give names such as Bolesław, Mieszko and later Kazimierz, Władysław and emperors ' names, such as Otto, Konrad ( Conrad ), and Henryk ( Heinrich ).

One of the most important events in those times was the foundation of the Diocese of Wrocław by the Polish Duke ( from 1025 king ) Bolesław the Brave in 1000, which, together with the Bishoprics of Kraków and Kołobrzeg, was placed under the Archbishopric of Gniezno in Greater Poland, founded by Otto III in 1000.

When Otto III reached is majority he again took to the field against the Lutici in the fall of 995, aided by the Polish Duke Bolesław I Chrobry.

Together, Otto III and Bolesław I worked to canonize Adalbert, becoming the first Slavic bishop to become a saint.

Between 7 and 15 March 1000, Otto III invested Bolesław I with the titles frater et cooperator Imperii (" Brother and Partner of the Empire ") and populi Romani amicus et socius (" Friend and ally of Rome ").

Otto III gave Bolesław a replica of his Holy Lance ( part of the Imperial Regalia ) and Bolesław presented the Emperor with a relic, an arm of Saint Adalbert in exchange.

Bolesław was an ally of Holy Roman Emperor Otto III who may have crowned him rex.

The exact circumstances of Bolesław I's ascension to the Ducal throne are unknown, but it is known that by June, he was the unquestioned ruler of Poland – as Otto III asked for his military aid in the summer of 992.

Since Otto III had intentions to renew the Empire based on a federal concept he called " Renovatio Imperii Romanorum ", and within that federal framework, Polish and Hungarian duchies were to be upgraded to eastern federati of the empire it was towards this end that the Emperor placed his Imperial crown on Bolesław I's brow and invested him with the titles frater et cooperator Imperii (" Brother and Partner of the Empire ") and populi Romani amicus et socius.

According to one source afterwards Bolesław I traveled with the Emperor to Aix-la-Chapelle where Otto III had the tomb of Charlemagne opened.

The future marriage of Bolesław I's son Mieszko to Richeza (), niece of Otto III, was also probably agreed upon at this point.

Probably already in 1000 during the Congress of Gniezno, was made an agreement between Bolesław I the Brave and Emperor Otto III.

Due to the childlessness of Otto III, the seven daughters of his sister Mathilde ( the only of Otto II's daughters who married and produced children ), were the only potential brides for Mieszko, Bolesław I's son and heir ; the oldest of Otto III's nieces, Richeza, was the chosen one.

However, the unexpected death of Otto III in 1002 and the reorientation of the Holy Roman Empire politics by his successor Henry II, the wedding is delayed until 1012, when Bolesław I demanded the wedding and sent his son to Germany with gifts to his bride's family, who at that time quarreled with Henry II for Mathilde's dowry.

It is here that the Congress of Gniezno took place in the year 1000 AD, during which Bolesław I the Brave, Duke of Poland, received Holy Roman Emperor Otto III.

Participants included Bolesław III himself, as well as Bohemian princes of the Premyslid line: Vladislaus I, Otto II the Black and Soběslav I.

Following an accord made between Prince Bolesław and Wartislaw I, Otto set out on a first stage of Christianization of the region.

Because of this Polish Prince Bolesław III was preparing a massive penal expedition that may have spoiled all the earlier accomplishments of missionary work by Bishop Otto.

Once the missionary activities of Otto of Bamberg took root Bolesław III began to implement an ecclesiastical organization of Pomerania.

The Congress of Gniezno ( or Gnesener Übereinkunft, ) was an amical meeting between the Polish duke Bolesław I Chrobry and Emperor Otto III, which took place at Gniezno on March 11, 1000.