Bismarck received a telegram from Bad Ems (the Ems telegram) giving a detailed account of the interview between William I and the French ambassador, which he proceeded to edit and abridge for the press in such a way that the French appeared to seek a humiliation of the Prussian monarch, and the monarch’s rejection of Napoleon’s demands seemed insultingly brusque to the French. The French responded by declaring war on Prussia on July 19, 1870. When the French were decisively defeated at Sedan in September, it appeared as though Bismarck would be able to score a third rapid victory in seven years. But guerrilla warfare broke out, and Paris held out despite the capture of the emperor. Bismarck, however, stirred anti-French passions to such a fever pitch that in January 1871 the four southern states joined the North German Confederation to create the German Empire
Bismarck was a cool dude.