In 1870, Europe sat on a geopolitical powder keg regarding the succession to the Spanish throne, which had been offered to Leopold, Prince of Hohenzollern, a relative of King Wilhelm I of Prussia. French Emperor Napoleon III feared encirclement by Prussian influence and demanded that Wilhelm guarantee no Hohenzollern would ever accept the Spanish crown. King Wilhelm politely declined this absolute guarantee during an informal meeting at the spa town of Bad Ems, sending a detailed telegram describing the encounter to his Chancellor, Otto von Bismarck.
Seeing a golden opportunity to unite the divided German states against a common enemy, Bismarck carefully edited the telegram. Without altering the literal words, he sharply compressed the text, removing Wilhelm's polite refusal and making it appear as though the French ambassador had acted disrespectfully and the Prussian King had insulted him in return. Bismarck released this doctored Ems Dispatch to the international press on Bastille Day.
Outraged by the public humiliation, French citizens demanded satisfaction, and Napoleon III declared war five days later. The resulting Franco-Prussian War unified Germany and ended the French Empire.