Russia enters the World War in response…

Russia enters the World War in response to Austria-Hungary's declaration of war on Russia's ally Serbia, and fights across multiple fronts while isolated from its Triple Entente allies.

The Brusilov Offensive of the Imperial Russian Army in 1916 almost completely destroys the Austro-Hungarian Army, but the already-existing public distrust of the regime is deepened by the rising costs of war, high casualties, and rumors of corruption and treason.

All this forms the climate for the Russian Revolution of 1917, carried out in two major acts.

Nicholas II is forced to abdicate in early 1917; he and his family are imprisoned and later executed in Yekaterinburg during the Russian Civil War.

The monarchy is replaced by a shaky coalition of political parties that declares itself the Provisional Government.

The Provisional Government proclaims the Russian Republic in September.

On 19 January [O.S. 6 January], 1918, the Russian Constituent Assembly declares Russia a democratic federal republic (thus ratifying the Provisional Government's decision).

The next day the Constituent Assembly is dissolved by the All-Russian Central Executive Committee.