Bishopric of Ösel–Wiek

The Diocese of Osel - Wiek was founded in 1228 by Bishop Albert of Buxhoeveden on the Estonian island of Saaremaa.

From 1255 it was placed under the Archbishopric of Riga. It included except the island of Saaremaa and Hiiumaa parts of the island as well as today's Estonian mainland to the west, the one Wiek were then called. The seat was after several changes of Kuressaare. The bishops were to 1559 as Prince Bishops also princes of the empire. With the advent of the Reformation, the diocese was dissolved. 1560 Osel fell to the Kingdom of Denmark, during Dagö 1563 was incorporated into the Kingdom of Sweden. 1645 was also Osel to Sweden. The territory of the diocese was dissolved in 1721 after the Great Northern War in the Treaty of Nystad in full to the Russian Empire, where it remained until 1918.