Mainz Diocesan Feud

The Mainz Diocesan Feud (German: Mainzer Erzstiftsfehde), also known as the Baden-Palatine War (Badisch-Pfälzischer Krieg), took place in 1461/1462 and was a warlike conflict for the throne of the Electorate of Mainz.

In 1459 the Domkustos, Diether of Isenburg, was elected, with a small majority, beating Adolph of Nassau to become the new Archbishop of Mainz. Diether immediately had to join the so-called anti-Palatinate alliance which had fallen into a dispute in 1458 with the Count Palatine, Frederick I. Diether forged an alliance and marched to war against the Count Palatine, but lost the decisive battle of Pfeddersheim in July 1460.

Because Diether was able to achieve his papal confirmation only with some difficulty and by paying a large amount of money (Servitiengeld, 20,000 guilders), he opposed the political, legal, and financial demands of both Emperor and Pope. Pope Pius II thus sought his replacement by Adolph of Nassau who had been defeated in the 1459 election. He banished Diether on 21 August 1461 and declared him deposed, citing Diether's oppositional attitude towards the Church and Emperor Frederick III, Diether's reform efforts, and his demands for abolition of papal annates. Adolph of Nassau was appointed by the Pope as the new Archbishop of Mainz and enthroned on 1 October 1461. The city of Mainz, however, continued to support Diether, who refused to vacate the archbishop's throne.

Adolph allied himself with the Archbishop of Trier, John II of Baden; the Bishop of Metz, George of Baden; the Bishop of Speyer, John II Nix of Hoheneck; and Count Ulrich V of Württemberg. Margrave Charles I of Baden at first tried to mediate between the warring factions, then took the side of his brother, Bishop George of Metz, who was in Adolph's camp, thus precipitating the Baden-Palatinate war, an attempt to seize the disputed bishopric by force.

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