Town in Baden, and former state of the Holy Roman Empire.
Christianized about the 2nd century, and fortified by the Romans, 304, Constance became an imperial city in 1192, was the scene of the Sixteenth Æcumenical Council (1414-1418) and, from the 7th century until the Reformation, was the seat of the largest diocese in Germany, including among its bishops, Saint Conrad (934-975) and Saint Gebhard II (979-995).
From the 13th century, these prelates were princes of the German Empire, and had temporal jurisdiction over a principality of about 482 square miles, with a population of some 50,000, which principality was divided between Baden and Switzerland in 1802.
The diocese, which sustained great losses during the Reformation, was dissolved by Pope Pius VII in 1821.
New Catholic Dictionary