Cathedral chapter
The Cologne War, 1583–1589, was triggered by the 1582 conversion of the Archbishop-Prince Elector of Cologne, Gebhard, Truchsess of Waldburg, to Calvinism, and his subsequent marriage to Agnes of Mansfeld-Eisleben in 1583. When he refused to relinquish the Electorate, a faction of clerics in the Cologne Cathedral chapter elected another archbishop, Ernst of Bavaria, of the House of Wittelsbach.