The Russian Revolution was sparked by over a century of oppressive rule under the czars. Reforms under Alexander II were rolled back after his assassination in 1881. Nicholas II continued autocratic ways as industrialization increased unrest. World War I losses and food shortages led to the March Revolution of 1917, forcing Nicholas to abdicate. Bolsheviks under Lenin seized power that November, establishing the Soviet Union and signing a separate peace with Germany. A civil war ensued as the Bolsheviks fought opposition groups, establishing communist rule by 1921.