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."
Silesian Wars
In January 1762, however, Austria was suddenly abandoned by its chief ally upon the death of Empress Elizabeth of Russia. She was succeeded by the ardently pro-Prussian Peter III of Russia, who immediately recalled his armies from Berlin and Pomerania and made peace with Prussia. Peter was himself overthrown and assassinated that summer, but by then the war had again shifted in Prussia's favor. Both sides were nearing exhaustion, and peace talks to end the wider Seven Years' War began in late 1762. In the end, negotiators agreed on a return to "status quo ante bellum", confirming Prussia's control of Silesia in the February 1763 Treaty of Hubertusburg. Prussia also committed to support the election of Maria Theresa's son, Archduke Joseph, as Holy Roman Emperor.