Zbigniew (also known as Zbygniew;According to A. Brücknera, filologist, slavist, historian of literature and art culture. O. Balzer: Genealogia Piastów, p. 114. c. 1073Some sources gives date of birth after 1070 (WIEM Encyklopedia) and date of death 1112 (Gieysztor 1979, p. 138, 668). – 8 July 1113?M. Spórna, P. Wierzbicki: Słownik władców Polski i pretendentów do tronu polskiego, p. 501; B. Snoch: Protoplasta książąt śląskich, Katowice, 1985, p. 13, .), was a duke of Poland (in Greater Poland, Kuyavia and Masovia) during 1102–1107. He was the first-born son of Władysław I Herman by his first wife, whose identity is unknown.

Zbigniew's legitimacy was questioned, presumably due to his parents's marriage being conducted according to pre-Christian tradition, and after the birth of his half-brother Bolesław Wrymouth, he was set on an ecclesiastical career. At the end of the 11th century, when real power in the country was held by the Palatine Sieciech, the opposition of some Silesian magnates caused the return of Zbigniew to Poland and forced Władysław I to recognize him as his successor. The intrigues of Sieciech and Władysław I's second wife Judith Maria caused Zbigniew and his younger half-brother to become allies, and both, in the end, forced their father to divide the country between them and to exile the Palatine.

After the death of his father, Zbigniew obtained the northern part of the country as an equal ruler with Bolesław. However, conflicts between them arose because Zbigniew, as the elder, considered himself the sole rightful heir of the kingdom. He began to search for allies against Bolesław. During 1102–1106, a fratricidal war for supremacy ensued, in which Zbigniew suffered complete defeat and was forced to go into exile in Germany. Under the pretext of restoring him, Emperor Henry V invaded Poland in 1109, but was defeated at Głogów.

In subsequent years, Boleslaw failed to defeat Bohemia, and in 1111 had to make peace with it and with his overlord, the Emperor. One of the conditions of Henry V was the return of Zbigniew to Poland, where he received a minor domain. Shortly after his return Zbigniew was blinded and then died.

Early years Childhood Zbigniew was the child of Władysław and a Polish woman, who is believed by historians to have been below her husband's social rank. According to 15th century The Chronicle of Greater Poland ["Kronika wielkopolska"], she was member of the Prawdzic family, however it is unknown wheter Prawdzic clan had even existed at this point of time. This union took place ca. 1070 under Slavic rites without a church ceremony.M. Spórna, P. Wierzbicki: Słownik władców Polski i pretendentów do tronu polskiego, p. 499.K. Jasiński: Rodowód pierwszych Piastów. Poznań, 2004, p. 164. . Some scholars argue that the marriage, although made under pagan rites, was lawful. They claim that not until the end of the 12th century did the Papal legate Peter of Capua, who stayed in Poland during 1197, order that only marriages performed under Church rites (Latin: matrimonium in facie ecclesie contrahere) would be considered as legitimate, following the writings of the Rocznik krakowsk.J. Żylińska: Piastówny i żony Piastów, Warsaw 1975, p. 91.Many historians regarded Zbigniew's mother as the first wife of Władysław I. K. Jasiński: Rodowód pierwszych Piastów, p. 164.

The exact birth date of Władysław I Herman's first born son is unknown. According to Oswald Balzer, Zbigniew was born in the first half of the 1070s, and Gerard Labuda agrees on a birth date in the early 1070s, while Roman Grodecki argues for Zbigniew's birth taking place around 1073, and Kazimierz Jasiński for a birth date between 1070 and 1073.K. Jasiński: Rodowód pierwszych Piastów, p. 182.

Zbigniew's legitimacy was questioned by some members of the Catholic Church, who claimed he was the son of Władysław I's concubine.R. Grodecki claimed that this claim had a political origin to eliminate his right to the throne, and was encouraged by the Palatine Sieciech and Judith Maria. R. Grodecki, S. Zachorowski, J. Dąbrowski: Dzieje Polski średniowiecznej, vol. I, p. 130. However, having been born from the union seen as legitimate according to older customs, he was considered heir apparent by the Polish nobles; he was ultimately recognized as the rightful heir by Maur, the bishop of Kraków.

In 1079, after his older brother Bolesław II the Generous was deposed,According to Wincenty Kadłubek on 11 April 1079, Bolesław II killed Bishop Stanislaus of Kraków. For several months, the Prince struggled with the growing opposition. In the end, he had to go into exile. A. Gieysztor: Bolesław II Szczodry [in:] A. Garlicki (ed.): Poczet królów i książąt polskich, pp. 59–61. Władysław I became the ruler of Poland. By this time, he had probably already had Masovia as his own separate district.M.K. Barański pointed out that Władysław I could be only governor of Masovia instead of an independent ruler. M.K. Barański: Dynastia Piastów w Polsce, pp. 173–174. According to historians, the new ruler was quickly noted as incompetent, and the population began to miss the achievements of the exiled Prince.M.K. Barański: Dynastia Piastów w Polsce, p. 172. In 1080, Władysław I married Princess Judith, daughter of Duke Vratislaus II of Bohemia; Zbigniew's mother either had died by this point, or Władysład had their marriage dissolved.

Around 1086, Władysław I's rule in Poland was threatened by the coronation of his father-in-law, Vratislaus II, as King of Bohemia and Poland, who at the same time concluded an alliance with King Ladislaus I of Hungary.O. Balzer concluded that Vratislaus II's coronation took place on 15 June 1086, following the reports of Cosmas of Prague. O. Balzer: Genealogia Piastów, p. 108. W. Mischke, like many other medievalists, pointed out that the coronation of Vratislaus II was on 15 June 1085. W. Mischke: Polska korona królów czeskich (in Polish) [retrieved 30 July 2014], pp. 11–12, 27–29.The reports of Cosmas of Prague about the coronation of Vratislaus II as King of Poland are disputed by many historians. Medievalists consider this a mistake of the chronicler. See G. Labuda: Korona i infuła. Od monarchii do poliarchii, p. 13. A detailed argument that favored Vratislaus II's coronation is presented by W. Mischke. See W. Mischke: Polska korona królów czeskich (in Polish) [retrieved 30 July 2014], pp. 11–29. M. Spórna and P. Wierzbicki believe that the reports of Cosmas are authentic. The title of King of Poland was probably received from the Emperor, who claimed feudal sovereignty over this country. M. Spórna, P. Wierzbicki: Słownik władców Polski i pretendentów do tronu polskiego, p. 496.

Władysław I's legitimacy was questioned by the supporters of the exiled Bolesław II and his only son and rightful heir, Mieszko Bolesławowic. Afraid of losing his position, in 1086 Władysław I recalled his nephew (and his mother)R. Grodecki, S. Zachorowski, J. Dąbrowski: Dzieje Polski średniowiecznej, vol. I. pp. 127–128. from their Hungarian exile. Mieszko received the district of Kraków and later married (1088) a Rurikid princess.This arrangement was designed to keep the status quo. M. Spórna, P. Wierzbicki: Słownik władców Polski i pretendentów do tronu polskiego, p. 353.M. K. Barański: Dynastia Piastów w Polsce, p. 178. These moves led the opposition to stop questioning the legality of Władysław I's rule.M. K. Barański: Dynastia Piastów w Polsce, p. 175. The situation was further complicated by the prince because he didn't have a legitimate son. Zbigniew, his first-born son, couldn't be considered as heir, because he was a product of a union not recognized by the Church.R. Grodecki, S. Zachorowski, J. Dąbrowski: Dzieje Polski średniowiecznej, vol. I, p. 130.

Loss of primogeniture In 1086, Judith of Bohemia finally gave birth to a son, the future Bolesław III Wrymouth,O. Balzer and K. Jasiński advocated for 1086 as Bolesław's year of birth. O. Balzer: Genealogia Piastów, p. 119; K. Jasiński: Rodowód pierwszych Piastów, pp. 185–187. and with this, Zbigniew's situation changed dramatically. In that year, he was placed in the Canonry of Kraków, despite being too young to be ordained a priest. This position was likely arranged by Judith of Bohemia to keep Zbigniew away from the line of succession. Dowager Duchess Maria Dobroniega, Zbigniew's paternal grandmother, guided his ecclesiastical studies.K. Maleczyński, Bolesław III Krzywousty pp. 22–23.S. Trawkowski: Władysław I Herman [in]: Poczet królów i książąt polskich, Warsaw 1978, p. 67. It's known that the first teacher of Zbigniew was Otto, who later became Bishop of Bamberg. In addition to the religious teachings, he taught him dialectic, grammar and the works of Isidore of Seville.M. K. Barański: Dynastia Piastów w Polsce, p. 275. Due to his young age, Zbigniew hadn't received the customary priestly journey.S. Trawkowski: Władysław I Herman [in:] A. Garlicki (ed.): Poczet królów i książąt polskich, p. 67. The Encyklopedia Historia provides the information that Zbigniew was ordained only after he ended his studies in Kraków. A. Nawrot (ed.): Encyklopedia Historia, p. 738.

A few months after the birth of her son, Judith of Bohemia died. In 1089, Władysław I married again. The chosen bride was Judith Maria,M. Spórna, P. Wierzbicki: Słownik władców Polski i pretendentów do tronu polskiego, p. 229.O. Blazer placed the marriage in 1088. O. Balzer: Genealogia Piastów, p. 115. sister of Henry IV, Holy Roman Emperor and widow of the ex-King Solomon of Hungary; she was renamed Sophia, perhaps to distinguish herself from Władysław I's first wife. Zbigniew's relationship with her was a cold one.

The position of Bolesław as legitimate heir was still threatened by Mieszko Bolesławowic, who was popular with the Polish aristocracy. This probably contributed to his death in 1089, allegedly poisoned by order of Sieciech and Judith Maria.M. Spórna, P. Wierzbicki: Słownik władców Polski i pretendentów do tronu polskiego, p. 353. In that year, Zbigniew was sent to Saxony, thanks to the intrigues of his new stepmother. Once there he was placed in Quedlinburg Abbey,S. Trawkowski: Zbigniew [in]: Poczet królów i książąt polskich, Warsaw 1978, p. 72. where Judith Maria's sister Adelaide was Abbess. Probably while there he was finally ordained a priest.According to medievalists, Zbigniew was incarcerated in Quedlinburg and never accepted the ordination. M. K. Barański: Dynastia Piastów w Polsce, p. 180. As taking holy orders would render Zbigniew ineligible for the succession,P. Ksyk-Gąsiorowska: Zbigniew [in]: Piastowie. Leksykon biograficzny Kraków 1999, p. 72. .R. Grodecki believes that the Count Palatine Sieciech, supporter of Władysław I, and Judith Maria were responsible for Zbigniew's placement at the Abbey. R. Grodecki, S. Zachorowski, J. Dąbrowski: Dzieje Polski średniowiecznej, vol I, p. 129. Władysław I hoped to eliminate the two main pretenders to the throne, secure the inheritance of his legitimate son Bolesław and weaken the growing opposition against him.The opposition, who supported the rights of Mieszko Bolesławowic and Zbigniew, demanded the legal recognition of the two princes as pretenders to the throne. S. Szczur: Historia Polski – średniowiecze, p. 117.

Rule of Sieciech

During the stay of Zbigniew in Quedlinburg, his father, Władysław I, became dependent on his supporter, Count Palatine Sieciech, to whom Władysław probably owed his throne.R. Grodecki, S. Zachorowski, J. Dąbrowski: Dzieje Polski średniowiecznej, vol. I, p. 128. Sieciech was also the first guardian of Bolesław, still a minor. In his intrigues to take over control of the country, the Palatine was supported by the Prince's wife Judith Maria.K. Maleczyński: Bolesław III Krzywousty, p. 30.