The still-extant Diocese of Osnabrück, erected in 772, is the oldest see founded by Charlemagne, in order to Christianize the conquered stem-duchy of Saxony. The episcopal and capitular temporal possessions of the see, originally quite limited, grew in time, and its prince-bishops exercised an extensive civil jurisdiction within the territory covered by their rights of Imperial immunity. The Prince-Bishopric continued to grow in size, making its status during the Reformation a highly contentious issue.