The key event of the Russian revolution. During the coup in Petrograd, the Provisional Government was overthrown and the Soviet power established, which was enshrined by the decisions of the II All-Russian Congress of Soviets of Workers’ and Soldiers’ Deputies. Due to General Lavr Kornilov’s affair at the end of August 1917, the position of the Bolsheviks strengthened. They headed the Soviets in Petrograd (on September 9, 1917, Leon Trotsky was elected Chairman of the Petrograd Soviet of Workers’ and Soldiers’ Deputies), Moscow (on September 14, Viktor Nogin was elected Chairman of the Moscow Soviet of Workers’ Deputies), and other cities. In the middle of September 1917, Vladimir Lenin sent two letters to the Central Committee of the RSDLP(b) where he again talked about the urgent need to start the immediate preparations for the armed uprising, the idea of which had been adopted by the Bolsheviks at the VI Congress of the RSDLP(b) in early August 1917. In those letters he also demanded the Bolsheviks exit from the All-Russian Democratic Conference.

The Bolshevik leadership split into three groups according to their approach to the issue of the uprising. The moderates, including  Grigory Zinoviev and Leon Kamenev, were against the uprising; Trotsky and some others believed that it was necessary to time the uprising to the Second Congress of Soviets; Lenin considered it necessary to start an armed uprising as early as possible, and to this end he illegally returned to Petrograd from Finland. On October 10, at a secret meeting of the Central Committee, Lenin achieved the adoption of a resolution “On the current situation.” In it, the preparation for an armed uprising was recognized as urgent and necessary; only Grigory Zinoviev and Leon Kamenev voted against it.

On October 5, 1917, Alexander Kerensky announced the sending of most of the Petrograd garrison to the front, which caused strong discontent among the soldiers. On October 12, the Executive Committee of the Petrograd Soviet approved the decision to establish a Military Revolutionary Committee (MRC) to defend revolution from the new possible “Kornilov affair”. The MRC was housed in the same building of Smolny Institute as the Petrograd Soviet. Although the first chairman of the MRC was the Left SR Pavel Lazimir, it was the Bolsheviks who played a decisive role in its work. Under their leadership, the committee began to prepare for an armed uprising. It also included the Left SRs, several anarchists. With the help of MRC radical forces headed by Bolsheviks managed to establish communication with the Soldiers’ Committees of the Petrograd garrison units.

 On October 21, the meeting of Petrograd garrison regiments committees representatives recognized the authority of the Soviet as the only one in the city. After that the MRC started the appointing of its commissars to the military units, replacing the commissars of the Provisional government. On October 23, the garrison of the Peter and Paul Fortress defected to the MRC, control over the Kronverk arsenal was established. The distribution of weapons to the units of the Red Guard began. However, the leaders of the MRC and the Central Committee of the Bolsheviks refrained from the armed seizure of power, expecting the Second All-Russian Congress of Soviets the next day to form a new government of SRs, the Mensheviks and the Bolsheviks, and the Provisional Government to voluntarily resign. On the evening of October 24, Lenin illegally arrived at the building of the former Smolny Institute, and again insisted on decisive steps to overthrow the Provisional Government, necessarily before the opening of the Second Congress of Soviets.

On the morning of October 25, the units of the Petrograd garrison and detachments of the Red Guard occupied the key facilities of the capital, they faced virtually no resistance At 10 o’clock the MRC issued an appeal “To the Citizens of Russia”, to announce that the Provisional Government had been deposed, and the power had passed to the MRC of the Petrograd Soviet of Workers’ and Soldiers’ Deputies. At 11 o’clock Kerensky went to the headquarters of the Northern Front located in Pskov to seek military support. In the afternoon, Lenin, who did not wait for the Second All-Russian Congress of Soviets of Workers’ and Soldiers’ Deputies to open, addressed the deputies of the Petrograd Soviet and announced: “The Workers’ and peasants’ revolution, the need for which the Bolsheviks have been talking about, is complete.”

By 6 p.m. detachments of the Red Guards, soldiers and sailors surrounded the Winter Palace, where the Provisional Government was headquartered and demanded that the ministers surrender voluntarily. At 2.10 a.m. on October 26, about 400 people from the military revolutionary forces led by Vladimir Antonov-Ovseenko entered the Winter Palace, disarmed the last of the cadets who had protected it, arrested the ministers, and sent them to Peter and Paul Fortress. The power of the Provisional Government fell. The decisions of the Second Congress of Soviets of Workers’ and Soldiers’ Deputies confirmed the transfer of all power to the Soviets, and the Provisional Workers’ and Peasants’ Government (Council of People’s Commissars) was formed, headed by Vladimir Lenin.