[4] He entered the ecclesiastical profession and, after passing through its lower stages, from 1472 on was a member of the Mainz cathedral chapter, dean from 1475.

As a follower of Nicholas of Cusa and the ideas of Renaissance humanism, he appears to have been a firm supporter of law and order, an enemy of clerical abuses and a careful administrator of his diocese.

Henneberg is most remembered as an advocate of administrative reform in the Empire, including the implementation of the Ewiger Landfriede (eternal public peace) to put an end to internal feuds, secured by the jurisdiction of an Imperial Chamber Court.

As a member of the electoral college and archchancellor he had brought this question before the Reichstag diet during the reign of Emperor Frederick III.

He also urged the Imperial States to emulate the courage and union of the Swiss Confederacy and gained a temporary victory when the 1500 Reichstag at Augsburg established a council of regency (Reichsregiment) under his guidance,[2] making the Emperor "no more than an honorary figurehead" while the real power in the Empire was with Henneberg and the other prince-electors.