The Electorate of Mainz (Kurfürstentum Mainz or Kurmainz, Electoratus Moguntinus), previously known in English as Mentz and by its French name Mayence, was one of the most prestigious and influential states of the Holy Roman Empire. In the Roman Catholic hierarchy, the Archbishop-Elector of Mainz was also the Primate of Germany (primas Germaniae), a purely honorary dignity that was unsuccessfully claimed from time to time by other archbishops. There were only two other ecclesiastical Prince-electors in the Empire: the Electorate of Cologne and the Electorate of Trier. The Archbishop-Elector of Mainz was also archchancellor of Germany (one of the three component titular kingdoms of the Holy Roman Empire, the other two being Italy and Burgundy) and, as such, ranked first among all ecclesiastical and secular princes of the Empire, and was second only to the Emperor. His political role, particularly as an intermediary between the Estates of the Empire and the Emperor, was considerable. The episcopal see was established in ancient Roman times in the city of Mainz, which had been a Roman provincial capital, Moguntiacum. The first bishops before the 4th century have legendary names, beginning with Crescens. The first verifiable Bishop of Mainz was Martinus in 343. The ecclesiastical and secular importance of Mainz dates from the accession of St. Boniface to the see in 747. Boniface was previously an archbishop though without an assigned see, but that ecclesiastical status did not immediately devolve upon the see itself until his successor Lullus; during his reign Mainz became an archdiocese, in 781. Another early bishop of Mainz was Aureus of Mainz. The territory of the Electorate included several non-contiguous blocks of territory: lands near Mainz on both the left and right banks of the Rhine; territory along the Main River above Frankfurt (including the district of Aschaffenburg); the Eichsfeld region in Lower Saxony and Thuringia; and the territory around Erfurt in Thuringia.