archbishop-elector of Mainz, imperial chancellor and reformer, who worked unsuccessfully for an increase in the powers of the clerical and lay nobility at the expense of the Holy Roman emperor.

Berthold was elected archbishop of Mainz in 1484 and played a leading role in securing the election of Maximilian I, a Habsburg, as king of the Romans (prospective successor to the Holy Roman emperor) in 1486. With his appointment as imperial chancellor in 1493, he pursued a policy of internal reform for the next decade. The reform program presented to Maximilian by the nobility at the Diet of Worms (1495), almost certainly Berthold's work, prescribed the establishment of a permanent high court for the Reich and a 17-member aristocratic council of government.

Maximilian, trying to reestablish imperial authority, opposed the formation of a council, even though the Diet threatened to cut off funds for his war efforts; but, having granted the court in 1495, he finally granted the council also, in 1500. Because neither court nor council members were paid as promised, however, both soon dispersed, and these bodies in effect ceased to exist.