1790, Joseph was briefly succeeded by his younger brother Leopold VII. Leopold II (1790–1792) Joseph's death proved a boon for Austria, as he was succeeded by his younger brother, Leopold II, previously the more cautiously reforming Grand Duke of Tuscany. Leopold knew when to cut his losses, and soon cut deals with the revolting Netherlanders and Hungarians. He also managed to secure a peace with Turkey in 1791, and negotiated an alliance with Prussia, which had been allying with Poland to press for war on behalf of the Ottomans against Austria and Russia. While restoring relative calm to what had been a crisis situation on his accession in 1790, Austria was surrounded by potential threats. While many reforms were by necessity rescinded, other reforms were initiated including more freedom of the press and restriction on the powers of the police. He replaced his brother's police minister, Johann Anton von Pergen, with Joseph Sonnenfels an advocate of social welfare rather than control. Leopold's reign also saw the acceleration of the French Revolution. Although Leopold was sympathetic to the revolutionaries, he was also the brother of the French queen. Furthermore, disputes involving the status of the rights of various imperial princes in Alsace, where the revolutionary French government was attempting to remove rights guaranteed by various peace treaties, involved Leopold as Emperor in conflicts with the French. The Declaration of Pillnitz, made in late 1791 jointly with the Prussian King Frederick William II and the Elector of Saxony, in which it was declared that the other princes of Europe took an interest in what was going on in France, was intended to be a statement in support of Louis XVI that would prevent the need from taking any kind of action. However, it instead inflamed the sentiments of the revolutionaries against the Emperor. Although Leopold did his best to avoid war with the French, he died in March 1792. The French declared war on his inexperienced eldest son Francis II a month later. The Arts Vienna and Austria dominated European music during the late 18th and early 19th centuries, typified by the First Viennese School (Wiener Klassik). This was the era of Haydn, and Mozart's Vienna period extended from 1781 to 1791 during which he was court composer. Opera, particularly German opera was flourishing. Mozart wrote many German operas including the Magic Flute. Initially the pillars of the establishment—the monarchy, such as