Mieszko I, Duke of Cieszyn Mieszko I, Duke of Cieszyn Mieszko I of Cieszyn (, , ; also known as Mieszko I of Opole; 1252/56 – by 27 June 1315), was a Duke of Racibórz during 1282–1290 (with his brother as co-ruler) and the first Duke of Cieszyn since 1290 until his death. He was the oldest son of Władysław, Duke of Opole-Racibórz, by his wife Euphemia, daughter of Władysław Odonic, Duke of Greater Poland. Little is known about the early years of Mieszko I's life. His first documented mention was on 21 October 1258, when he appears together with his father and two younger
Mieszko Kazimierzowic "Gesta principum Polonorum" written in the early 12th century, put Mieszko third in order, among his brother. Modern historian, Janusz Bieniak, has supposed that Mieszko was the second son of Casimir I and was older than Władysław Herman, but most scholars disagree with this hypothesis. The date of Mieszko's birth was given by "Rocznik krakowski" (Kraków Annals). This source omitted dates of birth of Mieszko's brothers. Kazimierz Jasiński thought that "Rocznik" was started shortly before Mieszko's birth and this was the reason for absence of his older brothers. Przemysław Wiszewski supposed tha Casimir I chose Mieszko as his successor and