The immediate cause of the war resided in the candidacy of a Leopold of Hohenzollern-Sigmaringen, a Prussian prince, to the throne of Spain. France feared <answer>encirclement</answer> by an alliance between Prussia and Spain. The Hohenzollern prince's candidacy was withdrawn under French diplomatic pressure, but Otto von Bismarck goaded the French into declaring war by altering a telegram sent by William I. Releasing the Ems Dispatch to the public, Bismarck made it sound as if the king had treated the French envoy in a demeaning fashion, which inflamed public opinion in France.
What did France fear by an alliance between Prussia and Spain?
encirclement