The First World War, which had been going on since 1914, devastated the country. Even though it had a certain potential, the old system was not prepared for this kind of test, and, accordingly, collapsed. The standard of living of the people was rapidly falling, as well as the level of support for the authorities.
In the end, on February 23, 1917, a strike began in Petrograd, which turned into an uprising by the 27th. Then the troops began to go over to the side of the rebels, and the interim committee of the State Duma declared itself the power, fearing that otherwise the power would fall into the hands of the Council of Workers' and Soldiers' Deputies, formed on the same day.
Under the pressure of circumstances, on March 2, 1917, Nicholas 2 abdicated in favor of Mikhail, who, in turn, refused to accept it in full, stating that the Constituent Assembly should decide the fate of the country.
Although the republic was proclaimed only on September 1, 1917, March 3 can be considered the end of the monarchy.
The provisional government, co-opted by non-communist parties, did not last even a year. Indecision, internal struggle, the divergence of words and deeds, failures at the front, and simply bourgeois origins eventually pushed the masses away from the new state.
The regime has experienced 4 major shocks.
1. The April crisis, when the Ministry of Foreign Affairs supported the conduct of the war to a victorious end
2. June crisis associated with a failed offensive
3. July Crisis ("Half-rebellion" in the words of Trotsky)
4. Kornilov rebellion in august (failed attempt to establish a right-wing dictatorship in Russia)