Bishopric of Ösel-Wiek
|Status||Prince-Bishopric of Terra Mariana|
|Common languages||Low German, Estonian|
|Johannes V von Münchhausen|
|Historical era||Middle Ages|
|1 October 1228|
o Sold to Denmark
The Bishopric of Ösel-Wiek (Estonian: Saare-Lääne piiskopkond; German: Bistum Ösel-Wiek; Low German: Bisdom Ösel-Wiek; contemporary Latin: Ecclesia Osiliensis) was a Roman Catholic diocese and semi-independent prince-bishopric (parto of Terra Mariana, i.e. Livonia) in the Holy Roman Empire, covering what are now Saare, Hiiu and Lääne counties of Estonia.
The bishopric was created on 1 October 1228 as a Latin rite (initially exempt?) diocese by papal legate William of Modena and simultaneously as a state of Holy Roman Empire--making it a prince-bishopric--by Henry, King of the Romans (1220-1242; not Emperor). Due to the repeated shift of the seat of the bishops, it was also successively known as bishopric of Leal (Lihula) from 1234, Perona (Vana-Pärnu) from 1251, Hapsal (Haapsalu) Castle from 1279, and the seat shifted (alone) to the castle of Arensburg (Kuressaare) on the island of Ösel (Saaremaa); the cathedral and cathedral chapter (canons) remained in Hapsal. It was a suffragan diocese in the ecclesiastical province of the Metropolitan Archbishopric of Riga from 1253.
One of the five members of the Livonian Confederation, the state was administratively divided into two bailiwicks (Latin advocaciae, German Vogteien). The bishop was also the lord of the Teutonic Order over its fiefs on the bishopric's territory. From 1241 until 1343, Ösel (Saaremaa) Island was an autonomous part of Ösel-Wiek prince-bishopric (autonomy renewed 27 August 1255).
The principality ceased to exist in 1560 when its last prince-bishop, Johannes V von Münchhausen, sold it to Denmark, which vested executive power in royally appointed Governors (styled Lensmaend to 1654, then Statthalter). King Frederick II of Denmark's brother Magnus of Livonia, Duke of Holstein, obtained it as an appanage on 15 April 1560 and was elected bishop on 13 May 1560; the Danish dynasty being Lutheran, he abolished the diocese and assumed the secular feudal style Lord of Ösel (Stieffte Ozel und Wieck Herr) on 20 March 1567.