The Russian Revolution of 1917 deposed the czar and installed the Bolsheviks in power. After winning the civil war in Russia, the Bolsheviks established the Soviet Union in 1922.
Timelines of the Russian Revolution are often confusing because up until February 1918 Russia used a different calendar than the rest of the Western world. The 19th century, the Julian calendar, used by Russia, was 12 days behind the Gregorian calendar (used by most of the Western world) until March 1, 1900, when it became 13 days behind.
In this timeline, the dates are in the Julian "Old Style," with the Gregorian "New Style" ("NS") date in parentheses, until the change in 1918. Thereafter, all dates are in the Gregorian.