The October Revolution, officially known as the Great October Socialist Revolution under the Soviet Union, 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 19171923. 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 [O.S. 25 October]. It was the precipitating event of the Russian Civil War.

The October Revolution followed and capitalized on the February Revolution earlier that year, which had overthrown the Tsarist autocracy, resulting in a liberal provisional government. The provisional government had taken power after being proclaimed by Grand Duke Michael, Tsar Nicholas II's younger brother, who declined to take power after the Tsar stepped down. During this time, urban workers began to organize into councils (soviets) wherein revolutionaries criticized the provisional government and its actions. The provisional government remained unpopular, especially because it was continuing to fight in World War I, and had ruled with an iron fist throughout the summer (including killing hundreds of protesters in the July Days).

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 (O.S.; 23 October, N.S.), the Petrograd Soviet, led by Trotsky, voted to back a military uprising. On 24 October (O.S.; 6 November, N.S.) 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 (O.S.; 7 November, N.S.), 1917. The following day, the Winter Palace (the seat of the Provisional government located in Petrograd, then capital of Russia) 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. The historiography of the event has varied. The victorious Soviet Union viewed it as a validation of their ideology, and the triumph of the worker over capitalism. During Soviet times, revolution day was a national holiday, marking its importance in the country's founding story. On the other hand, the Western Allies saw it as a totalitarian coup, which used the democratic Soviet councils only until they were no longer useful. The event inspired many cultural works, and ignited communist movements across Europe and globally. Many MarxistLeninist parties around the world still celebrate October Revolution Day.

Jiangxi or Kiangsi, officially the Chinese Soviet Republic (CSR), was an East Asian unrecognized proto-state within the territory of China's Jiangxi (Kiangsi) province and the predecessor to the People's Republic of China. The state was proclaimed on 7 November 1931 by future Chinese Communist Party leader Mao Zedong and General Zhu De in the early stages of the Chinese Civil War.

The discontiguous territories included 18 provinces and 4 counties under CSR control. Its largest and base territory was the Jiangxi-Fujian Soviet. It also included the Northeastern Jiangxi, Hunan-Jiangxi, Hunan-Hubei-Jiangxi, Hunan-Western Hubei, Hunan-Hubei-Sichuan-Guizhou, Shaanxi-Gansu, Szechuan-Shensi, Hubei-Henan-Anhui and Haifeng-Lufeng Soviets.

Mao Zedong was both CSR state chairman and prime minister; he led the state and its government. Mao's tenure as head of a "small state within a state" gave him experience in mobile warfare and peasant organization; this experience helped him accomplish the Communist reunification of China during the late 1940s.The CSR was eventually destroyed by the Kuomintang (KMT)'s National Revolutionary Army in a series of 1934 encirclement campaigns. Following the Xi'an Incident of December 1936, the Communists and Kuomintang formed an uneasy "United Front" to resist Japanese pressure, which led to the Communists recognizing at least for the moment Chiang Kai-shek as China's leader and the official dissolution of the Soviet Republic on 22 September 1937 with remnants existing as Shaan-Gan-Ning Border Region formed by the leadership of the CSR.