War of the Priests The War of the Priests ( 1467 - 1479 , , ) was a conflict in the Polish province of Warmia between the King of Poland Casimir IV and Nicolaus von Tüngen who had been chosen as new Bishop of Warmia 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 . Political background . The Bishopric of Warmia was in the 14th century part of the Monastic State of the Teutonic Knights , but enjoyed autonomy and was administrated as a prince - bishopric . The bishops , often members of the Teutonic Order , were loyal to the order even in early 15th century , when the Teutonic Knights raised the tax es to pay for the resulting costs of Polish – Lithuanian – Teutonic War . Eventually , the order ' s policies and tax increases led to opposition within Prussia and to the foundation of the Prussian Confederation in 1440 by Prussia n cities who wanted to defend their rights against the order . The Prussian Confederation eventually asked for external aid and allied with the Polish king Casimir IV , asking to be incorporated into the Kingdom of Poland . This led to the Thirteen Years ' War ( 1454 – 1466 ) . The Bishop of Warmia Paul von Legendorf ( 1458 – 1467 ) joined the Prussian Confederation in the last year of the conflict ( 1466 ) . The Second Peace of Thorn ( 1466 ) put Royal Prussia under the suzerainty of the Polish King . As part of the treaty , the king of Poland had the right to approve the Bishop of Warmia , as chosen by the Warmian chapter . Election dispute . In 1467 , the chapter chose as bishop Nicolaus von Tüngen , while the Polish king promoted Wincenty Kiełbasa ( at the time Bishop of Chełm ) for the position . It was Tüngen who was approved by the Pope , but he was unable to take the seat " de facto " and instead resided in Riga . Unable to get the Pope ' s approval for Kiełbasa , Casimir changed tact and nominated Andrzej Oporowski , his chancellor , as bishop ( Tüngen was to receive the Bishopric of Kamień ) . Oporowski however , unlike Kiełbasa , did not have the support of the Prussian estates as he was not from the region . This resulted in a dispute in which Tüngen was supported by the Teutonic Order and Matthias Corvinus , the king of Hungary . With help from the Order Tüngen was able to come to Warmia in 1472 . In 1476 Corvinus invaded southern Poland and a year later Heinrich Reffle von Richtenberg , the Grand Master of the Order refused to provide military support to Casimir , his sovereign . Casimir responded by courting the support of the Prussian Estates and cities . He granted Chełmno Law to several cities , affirmed existing privileges and withdrew the candidature of Oporowski . As a result the Prussians re - swore their fealty to the King of Poland and refused to support the order . Likewise , Gdańsk , the largest city in Polish Royal Prussia declined to support to the Order and Corvinus . Military action . 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 . Tungen was forced to flee to Konigsberg ( " Królewiec " ) . At the same time , in April of 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 Tungen and the Grand Master were forced to pay homage to the Polish king . Settlement . The first " Treaty of Piotrków " ( in Piotrków Trybunalski ) ended the feud in 1479 . The Polish King accepted Nicolaus von Tüngen , who had been elected in 1467 , as bishop , and granted or confirmed several prerogatives of the bishopric . The bishop acknowledged the sovereignty of the Polish King over Warmia , obliged the chapter to elect only candidates " liked by the Polish King " and the Warmians had to pledge allegiance to him . Politically Warmia remained under lordship of the Polish crown .