Around the middle of the 18th century the balance of power in Europe shifted, with Russian victories against the Ottomans in the Russo-Turkish War (1768–1774) strengthening Russia and endangering Habsburg interests in that region (particularly in Moldavia and Wallachia). At that point Habsburg Austria started to consider waging a war against Russia. France, friendly towards both Prussia and Austria, suggested a series of territorial adjustments, in which Austria would be compensated by parts of Prussian Silesia, and Prussia in turn would receive Polish Ermland (Warmia) and parts of the Polish fief, Duchy of Courland and Semigallia—already under Baltic German hegemony. King Frederick II of Prussia had no intention of giving up Silesia gained recently in the Silesian Wars; he was, however, also interested in finding a peaceful solution — his alliance with Russia would draw him into a potential war with Austria, and the Seven Years' War had left Prussia's treasury and army weakened. He was also interested in protecting the weakening Ottoman Empire, which could be advantageously utilized in the event of a Prussian war either with Russia or Austria. Frederick's brother, Prince Henry, spent the winter of 1770–71 as a representative of the Prussian court at Saint Petersburg. As Austria had annexed 13 towns in the Hungarian Szepes region in 1769 (violating the Treaty of Lubowla), Catherine II of Russia and her advisor General Ivan Chernyshyov suggested to Henry that Prussia claim some Polish land, such as Ermland. After Henry informed him of the proposal, Frederick suggested a partition of the Polish borderlands by Austria, Prussia, and Russia, with the largest share going to Austria. Thus Frederick attempted to encourage Russia to direct its expansion towards weak and non-functional Poland instead of the Ottomans.