CONSTANCE, Bishopric. KONSTANZ.
From the early 7th century there was a Bishop in Constance, a city of southern Germany, which stands at the outlet to the lake of that name (Bodensee in German). The diocese was originally in the province of Besançon, but from 810 in Mainz. It came to cover what now are northeastern Switzerland, southern Baden-Württemberg, the southwestern corner of Bavaria, and the north of the Vorarlberg in Austria.
Though the diocese was vast, the Bishop’s temporal principality was small. His episcopal city became a Free Imperial City in the 13th century. The Bishop held lands around the Untersee, the southwestern arm of Lake Constance, and on the northern shores of the lake around the town of Meersburg.
Further down the Rhine he held small pockets of territory in the Klettgau, the district to the west of Schaffhausen. The Bishop continued to reside in the city of Constance until the Reformation there made him flee to Meersburg in 1526, and there he and his successors remained even after the Habsburg conquest of the city and its recatholicisation.
A fragment of the episcopal territory on the left bank of the Rhine became Swiss in 1798; the rest became part of Baden in 1802-3. The Bishopric itself also disappeared in the reordering of the Church in the years after the fall of Napoleon.