Catherine successfully waged two wars (1768-74, 1787-92) against the decaying Ottoman Empire and advanced Russia's southern boundary to the Black Sea. Russia annexed Crimea in 1783, and created the Black Sea fleet. Then, by allying with the rulers of Austria and Prussia, she incorporated the territories of the Polish–Lithuanian Commonwealth, where after a century of Russian rule non-Catholic, mainly Orthodox population prevailed during the Partitions of Poland, pushing the Russian frontier westward into Central Europe.