The Russian Revolution is the collective term for a pair of revolutions in Russia in 1917, which dismantled the Tsarist autocracy and led to the eventual rise of the Soviet Union. The Russian Empire collapsed with the abdication of Emperor Nicholas II, and the old regime was replaced by a provisional government during the first revolution of February 1917 (March in the Gregorian calendar; the older Julian calendar was in use in Russia at the time). In the second revolution that October, the Provisional Government was removed and replaced with a Bolshevik (Communist) government.