Background of the Winter War The background of the Winter War covers the period before the outbreak of the Winter War between Finland and the Soviet Union in 1939 – 1940 , stretching from Finland ' s Declaration of Independence in 1917 to the Soviet - Finnish negotiations in 1938 – 1939 . Before its independence , Finland was an autonomous grand duchy inside Imperial Russia . During the ensuing Finnish Civil War , the Red Guards , supported by the Russian Bolsheviks , were defeated . Fearful of Soviet designs , during the 1920s and 1930s , the Finns were constantly attempting to align themselves with Scandinavian neutrality , particularly with regard to Sweden . Furthermore , the Finns engaged in secret military co - operation with Estonia in the 1930s . While during the late 1920s and early 1930s relations with the Soviet Union became normalized to a degree , from 1938 on , the Soviets , anxious that Finland could be used as a springboard for an invasion , started negotiations to conclude a military agreement . At the same time , Soviet leader Joseph Stalin ' s desire to recover the territories of Tsarist Russia lost during the chaos of the October Revolution and the Russian Civil War made Finland an obvious target . Due to the nature of Soviet demands , which included the installation of Soviet military facilities on Finnish soil , these negotiations went nowhere . In August 1939 , the Soviet Union and Nazi Germany signed the Molotov – Ribbentrop Pact , in which Eastern European countries were divided into spheres of interest ; Finland belonged to the Soviet sphere of interest . In October 1939 , Stalin gained control of the Baltic states and turned his sights on Finland , confident that control could be gained without great effort . The Soviet Union demanded territories on the Karelian Isthmus , the islands of the Gulf of Finland and a military base near the Finnish capital Helsinki , similar to the demands presented in the previous years . The Finns again refused , and the Red Army attacked on 30 November 1939 . Simultaneously , Stalin set up a puppet government for the Finnish Democratic Republic , headed by the Finnish communist Otto Wille Kuusinen . Finnish politics before the war . First steps of the Republic . Finland had been the eastern part of the Swedish kingdom for centuries until 1809 , during the Napoleonic Wars , when Imperial Russia conquered and converted it into an autonomous buffer state within the Russian Empire to protect Saint Petersburg , the imperial capital . Finland enjoyed wide autonomy and its own Senate until the turn of the century , when Russia began attempts to assimilate Finland as part of a general policy to strengthen central government and unify the Empire by Russification . These attempts ruined relations and increased the support of Finnish movements vying for self - government . The outbreak of the First World War gave Finland a window of opportunity to achieve this . The Finns sought aid from both the German Empire and the Bolsheviks to that end , and on 6 December 1917 , the Senate of Finland declared the country ' s independence . The new Bolshevik Russian government was weak , and soon the Russian Civil War would break out . Bolshevik leader Vladimir Lenin could spare no troops or attention for Finland , and consequently , Soviet Russia recognized the new Finnish government just three weeks after the declaration of independence . In 1918 , the Finns fought a short civil war , where the pro - Bolshevik Red Guards were armed by 7 , 000 to 10 , 000 Russian troops stationed in Finland . After the First World War , an inter - governmental organization , the League of Nations was founded . The League ' s goals included preventing war through collective security and settling disputes between countries through negotiation and diplomacy . Finland joined the League in 1920 . In 1920s and 1930s Finland was politically diverse . The Communist Party of Finland was declared illegal in 1931 , and the far - right Patriotic People ' s Movement ( IKL ) had a minor presentation of fourteen seats in the 200 - seat parliament . The middle ground , occupied by Conservatives , Liberals , Agrians and Swedish People , tended to cluster with the Social Democratic Party , whose leader , Väinö Tanner , was a strong proponent of the parliamentary system . By the late 1930s the Finnish export - oriented economy was growing , the country had almost solved its " right - wing problem " and Finland was preparing for the 1940 Summer Olympics . Finnish – German relations . During the closing stages of World War I , German - trained Finnish Jäger troops played a key role in the Finnish Civil War , while the German Baltic Sea Division also intervened late in the civil war . Jäger troops were volunteers from German - influenced circles , such as university students . This participation in the Finnish struggle for independence created close ties with Germany , but after the German defeat in the World War , Scandinavian relations became more important and the main goal of the Finnish foreign policy . Finnish - German relations cooled after the National Socialists rose to power in 1933 – Finns admired Imperial Germany , not the radical and anti - democratic Nazi regime . Finnish conservatives did not accept the state violence and anti - church policies of the Nazis . Still , there was sympathy for German aims to revise the Treaty of Versailles , although the official Finnish policy was reserved , especially after the German occupation of Czechoslovakia . Finland even recalled its ambassador for a short period . Finnish Nazis and ultranationalist parties such as the IKL achieved only minor support in several elections , especially in the aftermath of the failed Mäntsälä rebellion in 1932 . Finnish – Swedish co - operation . After the 1917 Finnish independence and the Civil War , the other Scandinavian countries would have been the best candidates for a political alliance . Swedo - Finnish cooperation represented a rich vein of shared history in the culture of both nations , and the Swedish - speaking Finns had a common language with Swedes . During the Civil War , however , Sweden briefly occupied the Åland Islands and later supported the local movement that wanted to secede from Finland and join the islands to Sweden . The dispute was resolved by the League of Nations in 1921 and the Åland remained Finnish , but were granted autonomy . Other obstacles to closer relations were the ongoing language strife on the status of the Swedish language in Finland . Sweden had also opposed the upper - class resistance movement against Russification . As a result , young Finnish men received their military training in Germany , generating the Jäger Movement . Nevertheless , Finnish – Swedish relations improved considerably before the Winter War . Finland sought security guarantees from the League of Nations , but did not have high expectations . Sweden was one of the founding members of the League , and consequently framed its military policies based on the League ' s principles of disarmament and sanctions . In the mid - 1920s the Finns established a special planning committee , called the Committee of Erich after its chairman Rafael Erich , which consisted of top politicians and officers , with the aim of exploring a possible military collaboration of Finland with other nations . The prime goal was co - operation with the Scandinavian countries , amongst which Sweden was the most important prospective partner . The Finnish and Swedish militaries engaged in wide - ranging co - operation , but it was more focused on the exchange of information and defence planning for the Åland islands than on military exercise s or materiel . The Finnish objective was to commit the Swedes by establishing a military - political joint venture in the Åland : if the Swedes would undertake to assist Finland in fortifying the islands , then an important and useful precedent might be set . The Government of Sweden was aware of the military co - operation , but carefully avoided committing itself to Finnish foreign policy . Secret military co - operation with Estonia . Finnish – Estonian relations were closest diplomatically after the Estonian Freedom War in the 1920s , but cooled afterwards . Military relations however remained close . From the Finnish point of view , the close relations with Estonia did not exclude the Scandinavian neutrality policy . Nevertheless , the military relations were top secret , and the countries held joint military exercises . The central aim was to prevent the Soviet Baltic Fleet from freely using its strength in the Gulf of Finland against either country . Estonia also sought public security guarantees and signed the Baltic Entente in 1934 with Latvia and Lithuania . Relations with the United Kingdom and France . After the collapse of Imperial Germany in November 1918 , the Finns sought new political partners . The United Kingdom had been a significant trading partner since the 18th century , and the Finns worked to improve the relations for the next two decades . In the 1930s Finland purchased Thornycroft torpedo boats from the United Kingdom , and also refrained from buying bomber aircraft from Germany because of British protests , purchasing instead modern Bristol Blenheim s , which later served successfully during the Winter War . Relations with France were important after World War I and in the 1920s , as France played a leading role in the new European security arrangements . In the 1930s France started to fear the rise of Nazi Germany and initiated a rapprochement with the Soviet Union , which strained Franco - Finnish relations . However , during the Winter War France was one of the most important suppliers of military materiel . Finnish defence plans . The Finnish Defence Forces ' military operation plan against the Soviet Union was named " Venäjän keskitys " ( " Russian Concentration " ; VK ) in the 1920s . In the latest 1934 plan , the Finns saw two possible scenarios . In the VK1 scenario , the Soviets would mobilize all along their western border , and would deploy only limited forces against Finland . In this case the Finns would make counterattacks across the border . The VK2 scenario envisaged a much more unfavourable situation for the Finns . The main defense line would be on the Karelian Isthmus , the Finnish forces would repel Soviet attacks in favourable positions , and destroy the enemy by counterattack s . In the Winter War , the VK2 scenario was flexible and its basis proved correct , but the Finnish General staff badly underestimated the numerical superiority of the Red Army . Finland had a limited defence budget after its independence and especially in the 1930s . Consequently , the Finnish Defence Forces were lacking military materiel in almost all branches . Much of the military ' s materiel was outdated , and even proved unsuitable for the field during the Winter War . During the Winter War the material situation improved , but it still lagged behind the more modern and well - equipped Red Army . Soviet – Finnish relations . Diplomatic relations . The relationship between the Soviet Union and Finland had been tense — a legacy of the two periods of forced Russification at the turn of the century and the failed Soviet - backed socialist rebellion in Finland , as well as incursions by groups of Finnish nationalists – the Viena expedition in 1918 and the Aunus expedition of 1919 – into Russian East Karelia . On 14 October 1920 , Finland and Soviet Russia signed the Treaty of Tartu , confirming the new Finnish - Soviet border as the old border between the autonomous Grand Duchy of Finland and Imperial Russia proper . In addition , Finland received Petsamo , with its ice - free harbour on the Arctic Ocean . The treaty did not prevent the Finnish government from allowing volunteers to cross the border to support the East - Karelian Uprising in 1921 however , nor expatriate Finnish communists from causing disturbances in Finland . In 1923 both countries signed the Border Peace Agreement , which normalized the border . In 1928 , the Soviet Union began collectivization in Ingria . During the collectivization and ethnic cleansing , the Soviets captured , killed and deported Ingrian peasants , provoking widespread criticism by the Finnish media in 1930 . Two years later , the nationalist Lapua Movement unsuccessfully attempted to overthrow the Finnish government in the Mäntsälä rebellion . Nevertheless , during the 1930s , the diplomatic climate between Finland and the Soviet Union gradually improved . From the 1920s , the Soviet Union had offered different non - aggression pacts with Finland but they were all rejected . Now the offer was renewed as part of a series of agreements with the countries on the Soviet Union ' s western border . In 1932 , the Soviet Union signed a non - aggression pact with Finland , re - affirmed in 1934 for ten years . Relations between the two countries remained largely " de minimis " however . While foreign trade in Finland was booming , less than one percent of it was with the Soviet Union . In 1934 , the Soviet Union joined the League of Nations , and later accepted other " progressive forces " beside . This change in Soviet attitudes , as well as internal politics in Finland , enabled a short thaw in relations in 1937 . Stalin and the protection of Leningrad . After the Russian civil war , Joseph Stalin was disappointed at the Soviet Union ' s inability to foment a successful revolution in Finland , and furthermore , the Bolsheviks struggle with national sentiments inside the Soviet Union . In 1923 , Stalin proclaimed that the main danger in national relations was Great - Russian chauvinism . He started the policy of Korenizatsiya , indigenisation , to promote national communist cadres for every nationality . However , from 1937 Stalin encouraged Russian chauvinism , implying the Russians were politically and culturally superior . The Soviet diplomacy turned towards the recovery of the territories of the Tsarist state . The Soviet Union used the Comintern to announce a doctrine where bourgeoisie equaled Fascism , and that Communism was the natural agency of the proletariat . In practice , this meant that anything other than Communism would be considered anti - Soviet and fascist . The Soviet foreign policy was a mixture of the ideology of world revolution and the traditional concerns of Russian national security . During the Stalin era , the Soviet agriculture production collapsed causing famines in 1932 – 1933 . Official output numbers of industrial production were used as propaganda to portray the Soviet Union as an economic miracle . Soviet propaganda also used cross - border comparisons with Finland , to represent the country as a " vicious and reactionary Fascist clique " . The Finnish Marshal C . G . E . Mannerheim and the leader of the Finnish Social Democrat Party Väinö Tanner were particular hate figure s . Stalin gained near - absolute power in 1935 – 1936 , leaving only army as self - governing , but its officers also became the target of purges during the Great terror in 1937 – 1938 . In the late 1930s , Stalin ' s Soviet Union was no longer satisfied with the status quo in its relations with Finland . This came as a result of a change in Soviet foreign policy , which now pursued the aim of recovering the provinces of Tsarist Russia lost during the chaos of the October Revolution and the Russian Civil War . The Soviets considered the old Empire to have had an optimal balance of security and territory , and their thoughts were shaped by a historical precedent : as the Treaty of Nystad of 1721 was intended to protect Tsarist Saint Petersburg from the Swedes , the re - acquisition of Finland would protect the now Bolshevik Leningrad from the rising power of Nazi Germany . While in 1938 Sweden was no longer a major threat against Russia , the Soviets had not forgotten the role that the Finnish - controlled Åland islands had played as a base of operations for the German Expeditionary Force in the Finnish Civil War . Finnish – Soviet negotiations . Negotiations from 1938 to early 1939 . In April 1938 , a junior diplomatic official named Boris Yartsev contacted the Finnish foreign minister Rudolf Holsti and prime minister Aimo Cajander , stating that the Soviets did not trust Germany and war was considered possible between the two countries . In such a war Germany might use Finland as a base for operations against the Soviet Union . The Red Army would not wait passively behind the border , but would rather " advance to meet the enemy " . If Finland were to fight against Germany , then the Soviet Union would offer all possible economic and military assistance . The Soviets would also accept the fortification of Åland islands , but demanded " positive guarantees " on Finland ' s position . The Finns assured Yartsev that Finland was committed to a policy of neutrality , and the country would resist any armed incursion . Yartsev was not satisfied with the reply , given Finland ' s military weakness . He suggested that Finland could cede , or lease , some islands in the Gulf of Finland along the seaward approaches to Leningrad , a suggestion the Finns rejected . Earlier in the mid - 1930s , the Soviet ambassador in Helsinki , Eric Assmus , and the Leningrad Bolshevik party leader Andrei Zhdanov , had presented a similar proposal . Negotiations continued during autumn 1938 . The Soviets reduced their demands : a Red Army operation was not an option anymore and the focus was shifted on securing the Gulf of Finland . The Soviets wanted to be informed of key elements of the Finnish – Estonian Gulf blockade , the secret military plan against the Baltic Fleet . Furthermore Yartsev suggested that the Finns fortify the Suursaari island , but that the Soviets would take care of its defence . During the negotiations , Rudolf Holsti resigned as foreign minister , although not for reasons associated with the negotiations , and his place was taken by Eljas Erkko . Holsti was rather anti - German , so the resignation set off rumours , quickly qualled by the Finnish government , that he had been forced to resign by a Finnish government sympathetic to the Germans . The Finns attempted to appear even - handed , and the interior ministry issued an order banning the extreme - right IKL . The ban was reversed by the Finnish courts as being unconstitutional . Many years later , the minister in charge at that time , Urho Kekkonen , admitted that this was a simple gesture , to suggest to Moscow that Finland did not harbour a German fifth column . By the winter of 1939 , the Soviets further reduced their demands and sent Boris Stein to negotiate . Stein and Erkko met five times . Erkko rejected the Soviet proposals , saying that the Soviet demands would mean the end of the Finnish neutrality policy and displease the Germans . When the chairman of the Finnish Defense Council C . G . E . Mannerheim was informed of the negotiations , he opined that Finland should give up the Suursaari islands because their defence would anyway be impossible during a war , but his arguments did not persuade the majority of the Finnish government . Stein departed Helsinki empty - handed on 6 April . The Finns had many reasons to turn down the Soviet proposals . Finland had started negotiations for a military co - operation with Sweden , and the Finns had great hopes for the joint Finnish – Swedish defense for the Ålands islands and did not want to jeopardize these negotiations . In addition , the violent collectivization , purges , show trials and executions in Stalin ' s Soviet Union had given the country a bad reputation . Furthermore , most of the Finnish Communist leadership in the Soviet Union was executed during the Great Purge . The Soviet Union did not therefore seem to be a reliable contracting party . The Soviet envoys sent to negotiate with Finns were officially of relatively low rank , but as Väinö Tanner put it later , the Finns assumed rightly that they represented of some higher organ of State , probably the Soviet secret police NKVD . Soviet – German alliance . On 23 August 1939 , the Soviet Union and Germany signed the Molotov – Ribbentrop Pact . Nominally , the pact was a non - aggression treaty , but it included a secret protocol in which the independent countries of Finland , Estonia , Latvia , Lithuania , Poland and Romania were divided into spheres of interest , with Finland falling to the Soviet sphere of interest . In the immediate aftermath of the Pact , the Scandinavian countries and Finland were relieved . The Germans and Soviets were now allies , and there was no German threat against the Soviet Union . But shortly afterwards , Germany invaded Poland and Great Britain and France declared war against Germany . Next , the Soviets invaded eastern Poland , and later Moscow requested that the Baltic states allow the establishment of Soviet military bases and the stationing of troops on their soil . The government of Estonia accepted the ultimatum , signing the corresponding agreement in September , while Latvia and Lithuania followed in October . Soviet demands in late 1939 . On 5 October the Soviet Union invited Finland to negotiations in Moscow . The Finnish government did not hasten to comply , like the Estonian government had earlier . Unlike the Baltic countries , the Finns started a gradual mobilization under the guise of " additional refresher training " . The Finnish government did not send the foreign minister , but its ambassador in Stockholm , J . K . Paasikivi . This was done on purpose , to limit his powers as a negotiator . In Moscow , Paasikivi met both Foreign Minister Vyacheslav Molotov and Stalin . The Soviets demanded that the frontier between the USSR and Finland on the Karelian Isthmus be moved westward to a point only east of Viipuri , Finland ' s second - largest city , to the line between Koivisto and Lipola . In addition , the Finns would have to destroy all existing fortifications on the Karelian Isthmus . Finland should also cede to the Soviet Union the islands of Suursaari , Tytärsaari , and Koivisto in the Gulf of Finland . In the north , the Soviets demanded the Kalastajansaarento peninsula . Furthermore , the Finns should lease the Hanko Peninsula to the Soviets for thirty years , and permit the Soviets to establish a military base there . In exchange the Soviet Union would cede Repola and Porajärvi from Eastern Karelia , an area twice as large as the territories demanded from the Finns . The Soviet offer divided the Finnish government . The foreign minister Eljas Erkko and the defence minister Juho Niukkanen rejected the offer , backed by the president Kyösti Kallio . J . K . Paasikivi and C . G . E . Mannerheim , together with Väinö Tanner – who was later appointed one of the Finnish negotiators – wanted to accept the Soviet offer . The Finns relied on military assistance from Sweden , and Eljas Erkko took part in the Stockholm assembly of Scandinavian leaders between 18 October and 19 October . There , Erkko met the Swedish foreign minister Rickard Sandler in private , and Sandler assured him that he would persuade the Swedish government to assist Finland during a possible war . During the actual war , however , Sandler failed in this task and resigned . Finland was totally isolated by a German and Soviet blockade , and attempted in October to obtain arms and ammunition in absolute secrecy by enlisting the German arms dealer Josef Veltjens . On 31 October , Molotov announced the Soviet demands in public , during a session of the Supreme Soviet . The Finns made two counteroffers – the first in 23 October and the second on 3 November . In both offers Finland would cede the Terijoki area to the Soviet Union , which was far less than the Soviets had demanded . The Finnish delegation returned home on November 13 , taking for granted that the negotiations would continue in the future . Beginning of war . Military preparations . The Soviet Union had started an intensive rearmament near the Finnish border in 1938 – 1939 . Finnish students and volunteers had spent the late summer 1939 improving the defensive structures across the Karelian Isthmus . On the Soviet side of the border , penal labour worked hard in order to add some density to sparse road and rail networks . In summer 1939 was an important phase of Soviet planning , told by Aleksandr Vasilevsky and Kirill Meretskov in their memoirs . The Supreme Council of War ordered the Commander of Leningrad Military District Merestkov to draft an invasion plan , instead of Chief of Staff Boris Shaposhnikov . The plan was adopted in July . Necessary assault troop deployments and commands were not initiated until October 1939 , though operational plans made in September called for the invasion to start in November . Stalin however was certain that the Finns would change their opinion under Soviet pressure and cede the demanded territories . The invasion plans were laid down by the Soviet General Staff under Boris Shaposhnikov and Alexander Vasilevsky . The Soviet timetable was clearly and rigidly defined , with little or no margin for error . The key date was 21 December , Stalin ' s sixtieth birthday . By then , the Finnish capital Helsinki would have been " freed of the Fascist oppression " . Andrei Zhdanov had already commissioned a celebratory piece from Dmitri Shostakovich , entitled " " Suite on Finnish Themes " " to be performed as the marching bands of the Red Army would be parading through Helsinki . On 26 November , the Soviets staged the shelling of Mainila , an incident in which Soviet artillery shelled area near the Russian village of Mainila and then announced that a Finnish artillery attack had killed Soviet soldiers . The Soviet Union demanded that the Finns apologize for the incident and move their forces 20 – 25 kilometres from the border . The Finns denied any responsibility for the attack and rejected the demands , calling for a joint Finnish - Soviet commission to examine the incident . The Soviet Union claimed that the Finnish response was hostile , and used it as an excuse to withdraw from the non - aggression pact . The Red Army assaults . On 30 November , Soviet forces invaded Finland with 27 divisions , totalling 630 , 000 men , bombed civilian boroughs of Helsinki and quickly reached the Mannerheim Line . The shelling of Mainila was a casus belli of the Soviet Union as it had withdrawn from non - aggression pacts on 28 November . Earlier , Nazi Germany had staged a similar incident to have an excuse to withdraw from the nonaggression pact with Poland . Later , the Soviet Union would used the Orzeł incident to challenge the neutrality of Estonia . Later , the Finnish statesman J . K . Paasikivi commented that the Soviet attack , without a declaration of war , violated three different non - aggression pacts : the Treaty of Tartu of 1920 , the Non - aggression Pact between Finland and the Soviet Union signed 1932 and again in 1934 , and further the Charter of the League of Nations . The invasion was judged as illegal by the League of Nations , which expelled the Soviet Union on December 14 . Following the Soviet attack , C . G . E . Mannerheim was appointed Commander - in - Chief of the Finnish Defense Forces . Furthermore the Finnish government changed as Risto Ryti was appointed the new prime minister and Väinö Tanner as foreign minister . On 1 December , the Soviet Union created a new government for Finland , henceforth to be called the Finnish Democratic Republic . It was a puppet regime headed by O . W . Kuusinen , and became known as the " Terijoki Government " , since the village of Terijoki was the first place " liberated " by the Red Army . The puppet regime was unsuccessful , and it was quietly discarded during the winter of 1940 . Contrary to Soviet expectations , from the beginning of the conflict , the working - class Finns stood behind the legal government . This national unity against the Soviet invasion was later called the " spirit of the Winter War " .