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."
Erzherzog Ferdinand Max-class ironclad
Both ships were still under construction at the outbreak of the Seven Weeks' War in June 1866; the shipyard workers quickly completed the vessels, albeit with old smooth-bore guns instead of the Krupp rifled breech-loaders that were intended. "Erzherzog Ferdinand Max" served as the flagship of the Austrian fleet under Rear Admiral Wilhelm von Tegetthoff. The two ships saw action at the Battle of Lissa in July 1866, where "Erzherzog Ferdinand Max" rammed and sank the Italian ironclad . This proved to be the turning point of the engagement, forcing the Italian commander, Admiral Carlo Pellion di Persano to withdraw. "Habsburg", however, was not seriously engaged during the battle. Neither ship received significant damage in the battle, and they spent the rest of the war patrolling the Adriatic against a possible sortie from the Italian fleet. After the war, the ships were disarmed and laid up.