Bloody Sunday, on January 22, 1905, was the catalyst for the Russian Revolution.

Vladimir Lenin was the leader of the Bolshevik Party and the main architect of the Russian Revolution.

The Kerensky Government was the provisional government that ruled Russia from February to October 1917.

The October Revolution, also known as the Bolshevik Revolution, took place in November 1917 and resulted in the Bolsheviks' seizure of power.

The Treaty of Brest-Litovsk was signed between Russia and Germany in March 1918, ending Russia's participation in World War I.

Communism was the new political system established in Russia after the revolution, based on the ideas of Karl Marx and Vladimir Lenin.

Vladimir Lenin was the first leader of the Soviet Union, serving from 1917 until his death in 1924.

The Cheka, later known as the NKVD and KGB, was the secret police force established by the Bolsheviks to suppress political opposition.

The New Economic Policy (NEP) was implemented by the Bolsheviks to revive the economy and allow for private enterprise.

Collectivization was the forced collectivization of agriculture implemented by Stalin in the 1930s, resulting in widespread famine and economic disruption.

The Five-Year Plans were a series of economic plans implemented by the Soviet Union to rapidly industrialize the country.

The Great Purge, also known as the Great Terror, was a series of political purges carried out by Stalin in the 1930s, resulting in the execution or imprisonment of millions of people.

The Molotov-Ribbentrop Pact was a non-aggression pact signed between the Soviet Union and Germany in August 1939, dividing Eastern Europe between the two powers.

The Winter War was a military conflict between the Soviet Union and Finland in 1939-1940, resulting in Finland's loss of territory.

The Grand Alliance was the military alliance formed between the Soviet Union, the United States, and the United Kingdom during World War II.