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."
Prince Henry of Prussia (1726–1802)
Henry successfully led Prussian armies as a general during the Third Silesian War (1756–1763, part of the Seven Years' War). He greatly distinguished himself during his brother's victory at the Battle of Prague and fought heroically during the Prussians' subsequent defeat at Kolin. After the Prussian Army's initial success against one wing of the joint Russian and Austrian Armies in the Battle of Kunersdorf, Henry urged his brother Frederick to stop attacking. The king, who had already sent a message of victory to Berlin, pressed the attack. The day ended with a virtually destroyed Prussian army, a virtually defenseless Kingdom of Prussia, and a complete victory by the Russo-Austrian force. Afterwards, Henry reorganized the routed Prussian forces. Frederick came to rely on his brother as commander of the Prussian forces in the east, Frederick's strategic flank. Henry later won his most famous victory at Freiberg in 1762, the final battle of the war between Austria and Prussia; during subsequent peace negotiations, Frederick wrote to him, "You alone have the honor of breaking down Austrian obstinacy."