William the Conqueror eldest son. William was the son of the unmarried Robert I, Duke of Normandy, by Robert's mistress Herleva. His illegitimate status and his youth caused some difficulties for him after he succeeded his father, as did the anarchy that plagued the first years of his rule. During his childhood and adolescence, members of the Norman aristocracy battled each other, both for control of the child duke and for their own ends. In 1047 William was able to quash a rebellion and begin to establish his authority over the duchy, a process that was not complete until about 1060. His marriage
Frederick William, Duke of Cieszyn Frederick William, Duke of Cieszyn Frederick William of Cieszyn (, , ; 9 November 1601 – 19 August 1625) was a Duke of Cieszyn since 1617 until his death. He was the third but only surviving son of Adam Wenceslaus, Duke of Cieszyn, by his wife Elisabeth, daughter of Gotthard Kettler, Duke of Courland. His mother died from childbirth complications ten days after his birth, on 19 November 1602. Since his early years, Frederick William's education was entrusted to the Silesian humanist Baltzar Exner. In 1611 Duke Adam Wenceslaus decided to convert to the Catholicism, and all the Protestant members