How did the Russian Revolution of 1917 restore Finland's autonomy?

Following the Russian Revolution in March 1917, Finland regained its autonomy as the collapse of the imperial Russian government created a power vacuum. A coalition government, or Senate, assumed rule of the country.12

In July 1917, the Finnish Parliament passed a law stipulating that all authority previously held by the Russian emperor—excluding matters of defense and foreign policy—would henceforth be exercised by the Finnish Parliament itself. This transition toward self-governance set the stage for full sovereignty; following the Bolshevik takeover of Russia in November 1917, the Finnish Parliament issued a formal declaration of independence on December 6, 1917. This declaration was subsequently recognized by Vladimir Lenin and his government on December 31, 1917.12