Tüngen received the pope's agreement for his nomination on 4 November 1468 and obtained the bishop's insignia in Rome.
The nominee was not allowed to assume his office because of protests from the clergy and people of Warmia and the Prussian Estates.
Supported by the Teutonic Knights, Tüngen gained control of most of Warmia's castles and towns.
He also gained the support of the king of Hungary, Matthias Corvinus, then in conflict with Poland, entrusting him with protecting the bishopric.
In 1479, an agreement reached between Casimir II and Matthias Corvinus further weakened Tüngen's position.
These efforts were interrupted by his death, yet his will was respected when the diocese chapter selected Watzenrode as the next bishop, taking advantage of the fact that the 1479 agreement did not specify which candidate was to be chosen.