The 1917 October Revolution was the first ever won by revolutionaries advocating a socialist society. By the beginning of 1917 the majority of the Russian people were extremely discontented with the czar's regime. The Union of Soviet Socialist Republics (USSR) was composed of fifteen union republics, the largest of which was Russia, which was home to 52 percent of the USSR's population and included 76 percent of the land area. Before the Bolshevik Revolution, Russia was a vast empire ruled by a hereditary emperor, the czar, who governed the Russian people as well as many other nationalities and lands that later were incorporated into the USSR. Many in Eastern European countries considered Communist Party rule an aspect of Russian domination and a suppression of both nationalist aspirations and democratic ideals. The Orange Revolution occurred during the 2004 presidential election in the Ukraine, the second most populous, after Russia, of the former Soviet republics.