The October Revolution, also known as the Bolshevik Revolution, was a revolution in Russia led by the Bolshevik Party of Vladimir Lenin that was a key moment in the larger Russian Revolution of 1917–1923. It was the second revolutionary change of government in Russia in 1917. It took place through an armed insurrection in Petrograd (now Saint Petersburg) on 7 November 1917. It was the precipitating event of the Russian Civil War.

Events came to a head in the fall as the Directorate, led by the left-wing Socialist Revolutionary Party, controlled the government. The left-wing Bolsheviks were deeply unhappy with the government, and began spreading calls for a military uprising. On 10 October 1917, the Petrograd Soviet, led by Trotsky, voted to back a military uprising. On 24 October, the government shut down numerous newspapers and closed the city of Petrograd in an attempt to forestall the revolution; minor armed skirmishes broke out. The next day a full scale uprising erupted as a fleet of Bolshevik sailors entered the harbor and tens of thousands of soldiers rose up in support of the Bolsheviks. Bolshevik Red Guards forces under the Military-Revolutionary Committee began the occupation of government buildings on 25 October 1917. The following day, the Winter Palace was captured. As the Revolution was not universally recognized, the country descended into the Russian Civil War, which would last until 1923 and ultimately lead to the creation of the Soviet Union in late 1922.