But Bismarck saw that they must put themselves willingly under Prussia if the German Empire was to be a stable concern; he therefore left them alone to think it over for a while.

Sooner or later they would have to come in, since now that Austria had been excluded there remained only the choice between dependence on France and union with Prussia.

Bismarck deliberately played upon South Germany's fear of France, and Napoleon III's restless foreign policy admirably seconded his efforts.

But a war was necessary to bring matters to a head.

The opportunity came in 1870, and Bismarck was able to make it appear a war not of his own choosing.