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."
Austro-Hungarian Navy
Prior to the Austro-Hungarian Compromise of 1867, the Navy was referred to as the Imperial Austrian Navy or simply the Austrian Navy. It saw action in the French Revolutionary Wars, the Napoleonic Wars, the Second Egyptian–Ottoman War, the First and Second Wars of Italian Independence, the Second Schleswig War, and the Seven Weeks War as well as the simultaneous Third War of Italian Independence. Following Austria's defeat to Prussia and Italy during the Seven Weeks War, the Empire reformed itself into a dual monarchy with the Habsburg monarch ruling as Emperor of Austria over the western and northern half of the country that was the Austrian Empire, and as King of Hungary over the Kingdom of Hungary. The Austro-Hungarian Compromise of 1867 also transformed the Austrian Navy into the Austro-Hungarian Navy. Largely neglected by the Empire in its early years, the k.u.k. Kriegsmarine grew throughout the late 19th and early 20th centuries to become one of the largest navies in the Adriatic and Mediterranean Seas. By 1914 the k.u.k. Kriegsmarine had a peacetime strength of 20,000 personnel.
The k.u.k. Kriegsmarine saw action in the Boxer Rebellion, and the first shots of World War I were fired by the Austrian monitor "Bodrog", which bombarded Belgrade on 29 July 1914, the day after Austria-Hungary declared war on Serbia.