Photo de stock - 'A Duel to the Death', 1870. France, represented by Napoleon III (left) prepares to battle with Prussia, represented by Wilhelm I of Prussia, as Britannia attempts to mediate. This relates to the Franco-Prussian war of 1870. This all relates to the relatively recent abdication of Queen Isabella of Spain. The vacant throne had been offered to Prince Leopold of Hohenzollern-Sigmaringen. He was a distant relative of William of Prussia. Eventually, against Bismarck's advice, Wilhelm I of Prussia permitted the offer to be refused. Napoleon, who had not wanted a Prussian Prince enthroned in Spain, was not satisfied with this victory and demanded further guarantees that the matter would not later be resurrected. Prussia took umbrage, and the relationship deteriorated rapidly. France declared war on Prussia on 19th July 1870, only to face a speedy defeat. From Punch, or the London Charivari, July 23, 1870.