Editing Winter War (section)

=== Finnish-Soviet relations and politics ===
{{Main|East Karelian uprising|Soviet–Finnish Non-Aggression Pact}}
{{See also|Independence of Finland}}
[[File:Northern europe november 1939.png|thumb|alt=A geopolitical map of Northern Europe in which Finland, Sweden, Norway and Denmark are tagged as neutral nations, and the Soviet Union is shown having military bases in the nations of Estonia, Latvia and Lithuania.|Geopolitical status in Northern Europe in November 1939<ref name="KR2007_10">[[#KilinRaunio2007|Kilin and Raunio (2007)]], p. 10</ref>{{sfnp|Hough|2019}}
{{legend|#98c807|Neutral countries}}{{legend|#636466|Germany and annexed countries}}{{legend|#d13814|Soviet Union and annexed countries}}{{legend|#ef9421|Neutral countries with military bases established by Soviet Union in October 1939}}]]
Until the early nineteenth century, Finland was the eastern part of the [[Kingdom of Sweden]]. From 21 February 1808 to 17 September 1809, the [[Russian Empire]] waged the [[Finnish War]] against the Kingdom of Sweden, ostensibly to protect the Russian capital, [[Saint Petersburg]]. Eventually Russia conquered and [[annexation|annexed]] Finland, and converted it into an [[autonomous entity|autonomous]] [[buffer state]].<ref name="Trotter2">[[#Trotter2002|Trotter 2002]], pp. 3–5</ref> The resulting [[Grand Duchy of Finland]] enjoyed wide autonomy within Russia until the end of the nineteenth century, when Russia began attempts [[Russification of Finland|to assimilate Finland]] as part of a general policy to strengthen the central government and unify the Empire by [[Russification]]. Those attempts were aborted because of Russia's internal strife, but they ruined Russia's relationship with Finland. In addition, support increased in Finland for self-determination movements.<ref name="Trotter_4-6">[[#Trotter2002|Trotter (2002)]], pp. 4–6</ref>

[[World War I]] led to the collapse of the Russian Empire during the [[Russian Revolution]] of 1917 and the [[Russian Civil War]]. On 15 November 1917, the [[Bolshevik]] Russian government [[Declaration of the Rights of the Peoples of Russia|declared that national minorities possessed the right of self-determination]], including the right to secede and form a separate state, which gave Finland a window of opportunity. On 6 December 1917, the [[Senate of Finland]] [[Finnish Declaration of Independence|declared the nation's independence]]. [[Soviet Russia]], later the [[Soviet Union]], recognised the new Finnish government just three weeks after the declaration.<ref name= "Trotter_4-6"/> Finland achieved full sovereignty in May 1918 after a [[Finnish Civil War|four-month civil war]] in which the conservative [[Whites (Finland)|Whites]] defeated the socialist [[Finnish Socialist Workers' Republic|Reds]] with the help of the [[German Army (German Empire)|Imperial German Army]], pro-German [[Jäger Movement|Jägers]], and some Swedish troops, in addition to the expulsion of Bolshevik troops.<ref name="JS2006_3">[[#Jow&Snod2006|Jowett & Snodgrass (2006)]], p. 3</ref>

Finland joined the League of Nations in 1920 and sought security guarantees, but Finland's primary goal was co-operation with the [[Scandinavian countries]], mainly Sweden, and it focused on the exchange of information and on defence planning (the joint defence of [[Åland]], for example), rather than on [[military exercises]] or on the stockpiling and the deployment of [[materiel]]. Nevertheless, Sweden carefully avoided committing itself to Finnish foreign policy.<ref name="Turtola1999a_21-24">[[#Turtola1999a|Turtola (1999a)]], pp. 21–24</ref> Finland's military policy included clandestine [[Finnish–Estonian defence cooperation|defence co-operation]] with [[Estonia]].<ref name="Turtola1999a_33-34">[[#Turtola1999a|Turtola (1999a)]], pp. 33–34</ref>

The period after the Finnish Civil War to the early 1930s was a politically unstable time in Finland because of the continued rivalry between the conservatives and the socialists. The [[Communist Party of Finland]] was declared illegal in 1931, and the nationalist [[Lapua Movement]] organised [[anticommunist]] violence, which culminated in a [[Mäntsälä rebellion|failed coup attempt]] in 1932. The successor of the Lapua Movement, the [[Patriotic People's Movement (Finland)|Patriotic People's Movement]], had a minor presence in national politics and never had more than 14 seats of the 200 in the [[Finnish Parliament]].<ref name="Edwards_26-27">[[#Edwards2006|Edwards (2006)]], pp. 26–27</ref> By the late 1930s, the export-oriented Finnish economy was growing and the nation's extreme political movements had diminished.<ref name="Edwards_18">[[#Edwards2006|Edwards (2006)]], p. 18</ref>

[[File:Soviet-finnish-nonaggression-pact (protokol 1934).jpg|thumb|The [[Soviet–Finnish Non-Aggression Pact]] was signed by [[Aarno Yrjö-Koskinen]] and [[Maxim Litvinov]] in Moscow 1932.]]
After Soviet involvement in the Finnish Civil War in 1918, no formal peace treaty was signed. In 1918 and 1919, Finnish volunteers conducted two unsuccessful military incursions across the Soviet border, the [[Viena expedition|Viena]] and [[Aunus expedition]]s, to annex areas in [[Karelia]] that according to the [[Greater Finland]] ideology would combine all [[Baltic Finnic peoples]] into a single state. In 1920, Finnish communists based in Soviet Russia attempted to assassinate the former Finnish [[White Guard (Finland)|White Guard]] Commander-in-Chief, Marshal [[Carl Gustaf Emil Mannerheim]]. On 14 October 1920, Finland and Soviet Russia signed the [[Treaty of Tartu (Russian–Finnish)|Treaty of Tartu]], confirming the old border between the autonomous Grand Duchy of Finland and Imperial Russia proper as the new Finnish–Soviet border. Finland also received [[Petsamo Province]], with its [[ice-free harbour]] on the Arctic Ocean.<ref>[[#Polvinen1987|Polvinen (1987)]], pp. 156–161, 237–238, 323, 454</ref><ref>[[#Engman07|Engman (2007)]], pp. 452–454</ref> Despite the signing of the treaty, relations between the two countries remained strained. The Finnish government allowed volunteers to cross the border to support the [[East Karelian uprising and Soviet–Finnish conflict of 1921–22|East Karelian uprising]] in Russia in 1921, and Finnish communists in the Soviet Union continued to prepare for revenge and staged a cross-border raid into Finland, the [[Pork mutiny|Pork Mutiny]], in 1922.<ref name="Turtola1999a_30-33">[[#Turtola1999a|Turtola (1999a)]], pp. 30–33</ref> In 1932, the [[Soviet–Finnish Non-Aggression Pact]] was signed between both countries, and it was reaffirmed for ten years in 1934.<ref name="Turtola1999a_30-33" /> Foreign trade in Finland was booming, but less than 1% of it was with the Soviet Union.<ref name="Edwards_31">[[#Edwards2006|Edwards (2006)]], p. 31</ref> In 1934, the Soviet Union also joined the League of Nations.<ref name="Turtola1999a_30-33" />