Answer the following question: Extract the answer to the question from the following context. Question: William I was the king of which country? Context: 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 encirclement 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 The Hohenzollern prince's candidacy was withdrawn under French diplomatic pressure, but Otto von Bismarck goaded the French into declaring war by altering a telegram sent by William I. Releasing the Ems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.
Answer:
Prussia