The conversion of the Archbishop of Cologne to Protestantism triggered religious and political repercussions throughout the Holy Roman Empire.
His conversion had widespread implications for the future of the Holy Roman Empire's electoral process established by the Golden Bull of 1356.
In this process, seven Imperial Electors—the four secular electors of Bohemia, Brandenburg, the Palatinate, and Saxony; and the three ecclesiastical electors of Mainz, Trier, and Cologne—selected an emperor.
The presence of at least three inherently Catholic electors, who collectively governed some of the most prosperous ecclesiastical territories in the Empire, guaranteed the delicate balance of Catholics and Protestants in the voting; only one other elector needed to vote for a Catholic candidate, ensuring that future emperors would remain in the so-called Old Faith.
The possibility of one of those electors shifting to the Protestant side, and of that elector producing an heir to perpetuate this shift, would change the balance in the electoral college in favor of the Protestants.

The conversion of the ecclesiastic see to a dynastic realm ruled by a Protestant prince challenged the principle of ecclesiastical reservation, which was intended to preserve the ecclesiastical electorates from this very possibility.
The difficulties of such a conversion had been faced before: Hermann von Wied, a previous prince-elector and archbishop in Cologne, had also converted to Protestantism, but had resigned from his office.
Similarly, Gebhard's predecessor, Salentin von Isenburg-Grenzau had indeed married in 1577, but had resigned from the office prior to his marriage.
Furthermore, the reason for his marriage—to perpetuate his house—differed considerably from Gebhard's.
The House of Waldburg was in no apparent danger of extinction; Gebhard was one of six brothers, and only one other had chosen an ecclesiastical career.
Unlike his abdicating predecessors, when Gebhard converted, he proclaimed the Reformation in the city of Cologne itself, angering Cologne's Catholic leadership and alienating the Catholic faction in the Cathedral Chapter.
Furthermore, Gebhard adhered not to the teachings of Martin Luther, but to those of John Calvin, a form of religious observation not approved by the Augsburg conventions of 1555.
Finally, he made no move to resign from his position as Prince-elector.

Affairs became further complicated when, on 2 February 1583, also known as Candlemas, Gebhard married Agnes von Mansfeld-Eisleben in a private house in Rosenthal, outside of Bonn.
After the ceremony, the couple processed to the Elector's palace in Bonn, and held a great feast.
Unbeknownst to them, while they celebrated their marriage, Frederick, Duke of Saxe-Lauenburg (1554–1586), who was also a member of the Cathedral Chapter, and his soldiers approached the fortified Kaiserswerth, across the river, and took the castle after a brief fight.
When the citizens of Cologne heard the news, there was a great public exultation.

Two days after his marriage, Gebhard invested his brother Karl with the duties of Statthalter (governor) and charged him with the rule of Bonn.
He and Agnes then traveled to Zweibrücken and, from there, to the territory of Dillingen, near Solms-Braunfels, where the Count, a staunch supporter, would help him to raise funds and troops to hold the territory; Adolf, Count von Neuenahr returned to the Electorate to prepare for its defense.

Gebhard clearly intended to transform an important ecclesiastical territory into a secular, dynastic duchy.
This problematic conversion would then bring the principle of cuius regio, eius religio into play in the Electorate.
Under this principle, all of Gebhard's subjects would be required to convert to his faith: his rule, his religion.
Furthermore, as a relatively young man, heirs would be expected.
Gebhard and his young wife presented the very real possibility of successfully converting a rich, diplomatically important and strategically placed ecclesiastical territory of a prince-prelate into a dynastic territory that carried
The conversion of the Archbishop of Cologne to Protestantism triggered religious and political repercussions throughout the Holy Roman Empire. His conversion had widespread implications for the future of the Holy Roman Empire's electoral process established by the Golden Bull of 1356. In this process, seven Imperial Electors—the four secular electors of Bohemia, Brandenburg, the Palatinate, and Saxony; and the three ecclesiastical electors of Mainz, Trier, and Cologne—selected an emperor. The presence of at least three inherently Catholic electors, who collectively governed some of the most prosperous ecclesiastical territories in the Empire, guaranteed the delicate balance of Catholics and Protestants in the voting; only one other elector needed to vote for a Catholic candidate, ensuring that future emperors would remain in the so-called Old Faith. The possibility of one of those electors shifting to the Protestant side, and of that elector producing an heir to perpetuate this shift, would change the balance in the electoral college in favor of the Protestants.
The conversion of the ecclesiastic see to a dynastic realm ruled by a Protestant prince challenged the principle of ecclesiastical reservation, which was intended to preserve the ecclesiastical electorates from this very possibility. The difficulties of such a conversion had been faced before: Hermann von Wied, a previous prince-elector and archbishop in Cologne, had also converted to Protestantism, but had resigned from his office. Similarly, Gebhard's predecessor, Salentin von Isenburg-Grenzau had indeed married in 1577, but had resigned from the office prior to his marriage. Furthermore, the reason for his marriage—to perpetuate his house—differed considerably from Gebhard's. The House of Waldburg was in no apparent danger of extinction; Gebhard was one of six brothers, and only one other had chosen an ecclesiastical career. Unlike his abdicating predecessors, when Gebhard converted, he proclaimed the Reformation in the city of Cologne itself, angering Cologne's Catholic leadership and alienating the Catholic faction in the Cathedral Chapter. Furthermore, Gebhard adhered not to the teachings of Martin Luther, but to those of John Calvin, a form of religious observation not approved by the Augsburg conventions of 1555. Finally, he made no move to resign from his position as Prince-elector.
Affairs became further complicated when, on 2 February 1583, also known as Candlemas, Gebhard married Agnes von Mansfeld-Eisleben in a private house in Rosenthal, outside of Bonn. After the ceremony, the couple processed to the Elector's palace in Bonn, and held a great feast. Unbeknownst to them, while they celebrated their marriage, Frederick, Duke of Saxe-Lauenburg (1554–1586), who was also a member of the Cathedral Chapter, and his soldiers approached the fortified Kaiserswerth, across the river, and took the castle after a brief fight. When the citizens of Cologne heard the news, there was a great public exultation.
Two days after his marriage, Gebhard invested his brother Karl with the duties of Statthalter (governor) and charged him with the rule of Bonn. He and Agnes then traveled to Zweibrücken and, from there, to the territory of Dillingen, near Solms-Braunfels, where the Count, a staunch supporter, would help him to raise funds and troops to hold the territory; Adolf, Count von Neuenahr returned to the Electorate to prepare for its defense.
Gebhard clearly intended to transform an important ecclesiastical territory into a secular, dynastic duchy. This problematic conversion would then bring the principle of cuius regio, eius religio into play in the Electorate. Under this principle, all of Gebhard's subjects would be required to convert to his faith: his rule, his religion. Furthermore, as a relatively young man, heirs would be expected. Gebhard and his young wife presented the very real possibility of successfully converting a rich, diplomatically important and strategically placed ecclesiastical territory of a prince-prelate into a dynastic territory that carried
Cologne War