After the Great Northern War, Ukraine was divided among a number of regional powers, and by the 19th century, the largest part of Ukraine was integrated into the Russian Empire, with the rest under Austro-Hungarian control. After a chaotic period of incessant warfare and several attempts at independence (1917–21) following World War I and the Russian Civil War, Ukraine emerged in 1922 as one of the founding republics of the Soviet Union. The Ukrainian Soviet Socialist Republic's territory was enlarged westward shortly before and after World War II, and southwards in 1954 with the Crimea transfer. In 1945, the Ukrainian SSR became one of the co-founding members of the United Nations. Ukraine became independent again after the dissolution of the Soviet Union in 1991.