Wikipedia
Bezprym
Bezprym (c. 986 – 1032) was a Duke of Poland during 1031–1032.
He was the eldest son of Bolesław I the Brave, King of Poland, but was deprived of the succession by his father, who around 1001 sent him to Italy, in order to become a monk at one of Saint Romuald's hermitages in Ravenna.
Expelled by his half-brother Mieszko II Lambert after the death of their father, in 1031 Bezprym became ruler of large areas of Poland following simultaneous attack of the German and Kievan forces and Mieszko II's escape to Bohemia. His reign was short-lived and, according to some sources, extremely cruel. He was murdered in 1032 and Mieszko II returned to the throne of Poland. It's speculated that Pagan Reaction began during his short reign