On 25 October 1917, (7 November according to the Gregorian calendar) radical socialists called Bolsheviks, led by Vladimir Lenin, Josef Stalin, and Leon Trotsky hijacked and precluded a wider socialist rebellion against the Russian Provisional republic led by Alexander Kerensky.
In February 1917, Tsar Nicholas II abdicated after the massive casualties sustained on the Eastern Front, mostly during the failed Brusilov Offensive in late 1916, and the resultant second and third order effects back home. A Provisional Government was formed, but to coordinate action of the middle and far left in the Provisional Government, a separate Petrograd Soviet, or worker’s council, was formed and chaired by Leon Trotsky. The Petrograd Soviet was based on other soviets that ruled locally in many parts of Russia. Petrograd, modern St. Petersburg and the capital of Russia at the time, was one of Russia’s most important cities, along with Moscow, and its soviet, and by default Trotsky, wielded outsized influence.
During the summer, the Provisional Government weathered several rebellions but in September and October 1917, Russia was wracked by massive strikes. On 23 October 1917, the Bolshevik Central Committee of the 2nd Congress of Soviets, which was meeting in Petrograd, resolved that the time was ripe for revolution, which was planned for two days later to coincide with the arrival of a flotilla of destroyers crewed by pro-Bolshevik sailors and marines.
On 25 October, Red Guards, specially formed paramilitaries consisting of armed factory workers, peasants, and deserters from the army and navy, seized strategic locations throughout the city in a near bloodless coup, as most of the Petrograd garrison joined the insurrection. That evening they seized an abandoned Winter Palace, the symbol of Russian Imperial rule. Kerensky fled earlier in the day to find military forces loyal to the Provisional Government specifically Cossack units outside the city. But since the Red Guards controlled the railroads, telegraphs, and the chokepoints around the city, Kerensky ended up borrowing a car from the American Embassy to flee. He managed to make his situation worse when some soldiers loyal to him fired on a unit that could have been persuaded to join his cause, and this act made him seem very Tsar-like in the eyes of many.
The next day, the Bolsheviks announced to the 2nd Congress of Soviets they had seized Petrograd and the Winter Palace. But instead of immediately forming a Constituent Assembly for a new constitution, the Bolsheviks announced that rule of Russia would be immediately given to the deputies of the local soviets. The Mensheviks and most of the Socialist Revolutionary Party walked out in protest, but Trotsky taunted them on the way out, “You are pitiful isolated individuals; you are bankrupts; your role is played out. Go where you belong from now on — into the dustbin of history!” But Trotsky was right, they were used, and when they were no longer needed, discarded. As many groups found out later much to their detriment (Lenin famously referred to them as “useful idiots”).
A new Constituent Assembly was elected from the Bolsheviks, the remaining Socialist Revolutionaries, and their allies, but even that was quickly disbanded when it proposed reforms that took power away from the soviets. Within a month, private property was confiscated, wages were fixed, and all forms of social hierarchy that didn’t stem from the barrel of a gun were abolished, such as military rank and noble or educational titles, the first secret police, the Cheka, were established, and the “hammer and sickle”, a proposed symbol unity between the worker and peasant, was adopted. The Bolsheviks would immediately seek terms with Imperial Germany, resulting with the Treaty of Brest-Litovsk, which ended Soviet Russia’s participation in the First World War, and began the Russian Civil War.