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."
Archduke Albrecht, Duke of Teschen
At the outbreak of the Seven Weeks' War in June 1866, Albrecht was named commander of the southern army facing the Italian forces of King Victor Emmanuel II. Albrecht was decisively victorious in the battle of Custoza (24 June 1866), but failed to exploit his victory when he neglected to pursue the beaten Italian "Army of the Mincio". Any advantages for the Austrians however were canceled out by the crushing defeat on 3 July at Königgrätz, where Ludwig von Benedek was surprised by the speed of Helmuth von Moltke's concentric advance into Bohemia.