That title (derived from German "herzog") then replaced the older Nordic "jarl", both translated into the Latin title "dux", (see introduction to list below). From the 13th century and until 1618, in some Swedish royal houses, when a king had more than one son, he gave each or some of them duchies to rule as fiefs. The geography of these duchies could be unclear, as they were not always within the boundaries of one province and could also be reallotted with territorial changes. Feuds between a king and ducal brothers were common, and ended at times in assassination and fratricide. There was only one non-royal Swedish duke, Benedict, Duke of Halland and Finland. After the Kalmar Union period, just before his death in 1560, King Gustav I continued the tradition by making his sons John, Magnus and Carl powerful dukes, together ruling much more of the kingdom than their older half-brother Eric, who had held a duchy in the southeast. When Eric became King Eric XIV, the imbalance of power his father had created became destructive. John, with the aid of Carl, eventually revolted, dethroned Eric and became king; Magnus proved unimportant due to mental health issues, but Carl's duchy of Södermanland prospered as a separate territory for several decades and also made his eventual rise to the throne possible. His duchy was inherited by his younger son, Carl Philip, who died in 1622 having been the last holder of one of the semi-autonomous Swedish duchies, which his brother, King Gustav II Adolph, officially abolished in 1618. During the subsequent rule of Queen Christina of Sweden, however, her cousin and heir Carl Gustav of the Palatinate-Zweibrücken was titled Duke of Öland by the Swedish sovereign herself, but her government refused to acknowledge that title officially. His father was created Duke of Stegeborg in 1651, a title that a younger brother of Carl Gustav's eventually inherited. In 1772, King Gustav III reinstated the appointment of dukes, now non-hereditary, for his brothers as courtesy titles, which added to their international prestige and domestic influence. Since then, all Swedish princes have been created dukes of a province at birth, as well as one Great Prince or Grand Duke of Finland (who died in infancy). During the 20th century, because of constitutional restraints, several princes gave up their royal titles for marriages that were not approved by the King (see Bernadotte af Wisborg).