Starting with John Frederick, the House of Griffin held this title until the last duke died in 1637, thus ending the considerable independence of the bishopric's territory from the rest of the Duchy of Pomerania.

While his mother appointed High Steward Ulrich von Schwerin as administrator of the duchy, he went to the court of Emperor Maximilian II at Vienna and participated in the war against the Ottoman Empire.

[3] Then 68-year-old Barnim XI decided in 1569 to withdraw from his position as a duke, and the duchy was internally partitioned among the male members of the House of Pomerania on 23 May 1569 in Jasenitz (now part of Police), which was approved by the Landtag in Wollin (now Wolin).

[4] In 1570, John Frederick, on behalf of Emperor Maximilian II, hosted the peace conference ending the Northern Seven Years' War between the Swedish Empire and Denmark–Norway.

[8] John Frederick also tried to elevate Pomerania's military status in the Upper Saxon Circle to match the position of Saxony and Brandenburg, yet unsuccessfully.