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."
Charles Gravier, comte de Vergennes
The objective of Chavigny and Vergennes in Lisbon was to keep Portugal from entering the War of the Austrian Succession on the side of Britain, a task that proved relatively easy as the Portuguese had little interest in joining the war. In 1743 Vergennes accompanied his uncle to the court of Charles VII who was the ruler of Bavaria and also held the title of Holy Roman Emperor. Charles VII was a key ally of the French in the ongoing war against Austria, and they were charged with keeping him in the war by assuaging his concerns which they accomplished successfully. They next were instrumental in the agreement of the Union of Frankfurt, a pact involving several German rulers to uphold Charles VII's interests. after Charles VII's sudden death in 1745, they strove to help his successor Maximilian III but were unable to prevent him from losing his capital at Munich and making peace with the Austrians at the Treaty of Füssen. In November 1745 Chavigny was relieved of his post, and returned to France accompanied by Vergennes. The following year they returned to Portugal to take up their previous posts there where they remained until 1749, unsuccessfully trying to negotiate a commercial treaty.