List of bishops of Mainz

The Elector of Mainz was one of the seven Prince-electors of the Holy Roman Empire. Both a ruling prince and an archbishop, the Elector of Mainz held a powerful position during the Middle Ages and retained some importance until the dissolution of the empire in 1806. The Elector of Mainz was president of the electoral college, arch-chancellor of the empire and primate of Germany. The origin of the title dates back to 747, when the city of Mainz was made the seat of an archbishop, and a succession of able and ambitious prelates, obtaining lands and privileges from emperors and others, made the district under their rule a strong and vigorous state. Among these men were important figures in the history of Germany such as Hatto I, Siegfried III, Peter of Aspelt, and Albert of Mainz There were several violent contests between rivals anxious to secure so splendid a position as the elector, and the power struggles of the archbishops occasionally moved the citizens of Mainz to revolt. The lands of the elector lay around Mainz, and were on both banks of the Rhine; their area at the time of the French Revolution was about 3200 sq. m. The last elector was Karl Theodor von Dalberg. The archbishopric was secularized in 1803, two years after the lands on the left bank of the Rhine had been seized by France. Some of those on the right bank of the river were given to Kingdom of Prussia and to the Grand Duchy of Hesse; others were formed into a grand duchy for the then Archbishop-Elector Dalberg. The archbishopric itself was transferred to the Principality of Regensburg.

The Archbishop of Mainz was an influential ecclesiastic and secular prince in the Holy Roman Empire between 780–782 and 1802. In Church hierarchy, the Archbishop of Mainz was the primas Germaniae, the substitute for the Pope north of the Alps. Aside from Rome, the See of Mainz is the only other see referred to as a "Holy See", although this usage became rather less common.

...
Wikipedia