Austro-Prussian War
The pretext for the conflict was found in the dispute between Prussia and Austria over the administration of Schleswig-Holstein, which the two of them had conquered from Denmark and agreed to jointly occupy at the end of the Second Schleswig War in 1864. When Austria brought the dispute before the German Diet and also decided to convene the Diet of Holstein, Prussia declared that the Gastein Convention had thereby been nullified and invaded Holstein. When the German Diet responded by voting for a partial mobilization against Prussia, Bismarck claimed that the German Confederation was ended. Crown Prince Frederick "was the only member of the Prussian Crown Council to uphold the rights of the Duke of Augustenburg and oppose the idea of a war with Austria which he described as "fratricide"". Although he supported unification and the restoration of the medieval empire, "Fritz could not accept that war was the right way to unite Germany."
Franz Joseph I of Austria
Franz Joseph I or Francis Joseph I (Franz Joseph Karl; 18 August 1830 – 21 November 1916) was Emperor of Austria, King of Hungary, and monarch of many other states of the Austro-Hungarian Empire, from 2 December 1848 to his death. From 1 May 1850 to 24 August 1866 he was also President of the German Confederation. He was the longest-reigning Emperor of Austria and King of Hungary, as well as the third-longest-reigning monarch of any country in European history, after Louis XIV of France and Johann II of Liechtenstein.