After the Prussian victory at the Battle of Königgrätz, and against the wishes of the Habsburgs, Bismarck succeeded in forming the North German Confederation as a military alliance in August 1866 without Austria.

Prince Leopold of Hohenzollern-Sigmaringen, supported by Prussian Minister-President Bismarck, acted as a candidate for royal succession in Spain.

Shortly after his candidature was accepted, however, Leopold of Hohenzollern-Sigmaringen, under the influence of his father, Prince Karl Anton, and the King of Prussia, William I, proposed the latter to the throne of Spain because France had threatened war with this candidacy.

The Emperor of the French, Napoleon III, however, did not want to be satisfied with the simple withdrawal of the candidacy, and sent his ambassador, Vincent Benedetti, to Bad Ems, to enter negotiations with the King of Prussia.

Napoleon demanded an official apology from Prussia and the general renouncement of the Hohenzollern and the Sigmaringen line to the Spanish throne also for the future, which King William I did not want to accept.

Benedetti was commissioned to demand William renounce any claim to the throne, and that he would forbid the Sigmaringen family from accepting the Spanish crown.

The 1871 event took place in the Hall of Mirrors at the Palace of Versailles, the ceiling on which was celebrated by Louis XIV, the Sun King, as a conqueror of German cities and states.

To conceal the subliminal controversies by mythical concepts, it was said, for example, that the crown had been "cowed by the flood of all German tribes".

The letter of the new Emperor Wilhelm I,[13] future Chancellor Otto von Bismarck, who served as the driver of the founding of the German Empire, and the public account made by historian Albert von Pfister,[14] who was present as a soldier, agreed to the fact that a field altar, instead of a throne, would be built on the Hall of Mirrors.