The Russian Revolution was a political movement in Russia that climaxed in 1917 with the overthrow of the Russian Tsar system and led to the establishment of the Soviet Union, which lasted until 1992. This movement was led by Vladimir Lenin based upon the ideas of Karl Marx and marked the beginning of the spread of communism in the twentieth century.
Dates are correct for the Julian calendar, which was used in Russia until 1918. It was twelve days behind the Gregorian calendar during the 19th Century and a day further behind during the 20th century.
See also: Russian Civil War