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."
Drache-class ironclad
Two years after the ships entered service, Austria joined Prussia in the Second Schleswig War against Denmark. "Drache" and "Salamander" were kept in the Adriatic to defend against a possible Danish attack, which failed to materialize. In 1866, Austria's erstwhile ally Prussia signed an alliance with Italy directed against Austria, beginning the Seven Weeks' War. The Austrian fleet was commanded by Rear Admiral Wilhelm von Tegetthoff, who attacked the Italian fleet as it attempted to capture the island of Lissa in the central Adriatic. In the ensuring Battle of Lissa, both ships were heavily engaged, with "Drache" inflicting fatal damage to the coastal defense ship , setting her on fire and ultimately destroying her. "Drache" did not escape unscathed, however, as she was hit by Italian shells numerous times; she lost her main mast, was temporarily set on fire, and her commander was killed. "Salamander" engaged the leading ships of the Italian line, though neither side inflicted serious damage on the other. Nevertheless, the loss of "Palestro" and the ironclad led the demoralized Italian fleet to disengage and retreat to their base at Ancona.