The War of the Priests was a conflict in the Polish province of Warmia between the King of Poland Casimir IV and Nicolaus von Tüngen, the new bishop of Warmia chosen – without the king's approval – by the Warmian chapter. The latter was supported by the Teutonic Knights, by this point vassals of Poland, who were seeking a revision of the recently signed Second Peace of Toruń.

In 1477 Martin von Wetzhausen, the new grand master of the order refused to make his oath of fealty to the Polish king and invaded Warmia, taking Chełm and Starogard Chełminski. In response, in 1478, Polish forces of King Casimir IV intervened militarily, besieging Braniewo. Under the command of Jan Biały and Piotr Dunin, the Polish forces occupied several cities in Warmia and Pomesania. The Teutonic Knights' military operations were hampered by the refusal of the Prussian Estates to support them. Tüngen was forced to flee to Königsberg (Królewiec). At the same time, in April 1479, the Polish and Hungarian kings came to an agreement and Corvinus withdrew from the anti-Polish alliance. As a consequence by July 1479, both Tüngen and the grand master were forced to pay homage to the Polish king.