The original diocese was founded about 970 by
Emperor Otto I in the
Billung March at
Oldenburg in Holstein (
Aldinborg or
Starigard), the former capital of the pagan
Wagri tribe. Oldenburg was then a
suffragan diocese of the
Archbishopric of Bremen, meant to missionize the
Obotrites. However, in the course of the 983 Slavic uprising (
see Lutici), the Wagri shook off Imperial supremacy and in 1038, the bishops were barred from entering their diocese. In 1052, the dioceses of
Ratzeburg and
Schwerin were split off from Oldenburg and no bishop was appointed after 1066. After the
Saxon count
Henry of Badewide had campaigned in the
Wagrian lands east of the
Limes Saxoniae in 1138/39, a new Bishop of Oldenburg,
Vicelinus, was appointed in 1149. Duke
Henry the Lion of
Saxony moved the seat of the diocese from Oldenburg to
Lübeck in 1160. When the Duchy of Saxony was dissolved with Henry's deposition in 1180, the Bishopric gained the status of
Imperial State (). Quarrels arose after the City of Lübeck gained
imperial immediacy in 1226 and as the territory of the state was centered on
Eutin, the town in 1309 became the residence of the bishops. The Bishopric did not attempt to fight the
Protestant Reformation. In 1531 the
Free City of Lübeck, instanced by
Johannes Bugenhagen, had turned Protestant, further inhibiting Catholic pastoring in the part of the Lübeck diocese under city rule. And in 1535 the Lübeck
cathedral chapter and subsequently all its diocesan territories adopted the
Lutheran confession. The
Prince-Bishop was elected by the chapter; since 1586, all
administrators of the prince-bishopric were members of the
Holstein-Gottorp line of the
House of Oldenburg. After the 1648
Peace of Westphalia, Lübeck was one of only two Protestant prince-bishoprics in the Empire (together with
Osnabrück, which however was alternately led by Protestant and Catholic bishops). ==Principality and Region of Lübeck==