The Finnish Declaration of Independence (Finnish: Suomen itsenäisyysjulistus; Swedish: Finlands självständighetsförklaring; Russian: Провозглашение независимости Финляндии) was adopted by the Parliament of Finland on 6 December 1917. It declared Finland an independent nation, among nations ending its autonomy within Russia as its Grand Duchy of Finland, with reference to a simultaneously delivered bill to the Diet to make Finland an independent republic instead.
Revolution in Russia
After the February Revolution and the abdication of Grand Duke Nicholas II on 2 March (15 March N.S.) 1917, the personal union between Russia and Finland lost its legal base – at least according to the view in Helsinki. There were negotiations between the Russian Provisional Government and Finnish authorities.
The resulting proposal, approved by the Provisional Government, was heavily rewritten in the Finnish Parliament and transformed into the so-called Power Act (Finnish: Valtalaki, Swedish: Maktlagen), whereby the Parliament declared itself to now hold all powers of legislation, except with respect to foreign policy and military issues, and also that it could be dissolved only by itself. At the time of the vote it was believed that the Provisional Government would be quickly defeated by the rebellion in Saint Petersburg. The Provisional Government survived, however, disapproved of the Power Act and dissolved the Parliament.
After new elections and the ultimate defeat of the Provisional Government in the October Revolution, the Finnish Parliament decided to set a three-man regency council, based on Finland's Constitution, and more precisely on clause §38  of the old Instrument of Government of 1772, which had been enacted by the Estates after Gustav III's bloodless coup. This paragraph provided for the election of a new monarch in case of the extinction of the royal line and was interpreted in Finland as vesting sovereignty in the estates, later the Parliament, in such an interregnum. The regency council was however never elected because of the strong opposition of Finnish socialists and their general strike which demanded for more radical action.
On 2 November (15 November N.S.) 1917, the Bolsheviks declared a general right of self-determination, including the right of complete secession, "for the Peoples of Russia". On the same day the Finnish Parliament issued a declaration by which it assumed, pro tempore, all powers of the Sovereign in Finland.
The old Instrument of Government was however no longer deemed suitable. Leading circles had long held monarchism and hereditary nobility to be antiquated, and advocated a republican constitution for Finland.
The Senate of Finland, the government that the Parliament had appointed in November, drafted a Declaration of Independence and a proposal for a new republican Instrument of Government. Chairman of the Senate (a.k.a. Prime minister) Pehr Evind Svinhufvud read the Declaration to the Parliament on 4 December. The Declaration of Independence was technically given the form of a preamble of the proposition, and was intended to be agreed by the Parliament, which adopted the Declaration on 6 December.
On 18 December (31 December N. S.) the Soviet Russian government issued a Decree, recognizing Finland's independence, and on 22 December (4 January 1918 N. S.) it was approved by the highest Soviet executive body, the All-Russian Central Executive Committee (VTsIK).
The Declaration and 15 November
With reference to the declaration of 15 November, the declaration says:
These three countries were occupied by, and annexed into, the Soviet Union (1940-1941, 1944-1991). See Occupation of the Baltic states.
The Finnish Senate: