The Russian Revolution was caused by social, political, economic, and military factors in the early 20th century. Dissatisfaction with the absolute rule of the Czars grew as most Russians lived in poverty with poor working conditions and limited freedoms. This led to the overthrow of the Czars in 1917 and the establishment of a Communist government led by Lenin and the Bolsheviks who promised reforms. However, the new government struggled with ongoing World War I and a subsequent civil war, leaving Russia in a weakened state. Stalin later consolidated power and ruled the Soviet Union as a totalitarian dictator, implementing repressive policies that killed millions and strictly controlled all aspects of life.