I want to know the answer to the following question:
What did France fear by an alliance between Prussia and Spain?
All the background I'm provided with is that "The Hohenzollern prince's candidacy was withdrawn under French diplomatic pressure, but Otto von Bismarck goaded the French into declaring war by altering a telegram sent by William I. Releasing the Ems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.". Is that enough to answer the question?