Photo via Pexels. A Finnish winter forest, the kind of terrain the Winter War was fought in.
On the morning of 30 November 1939, Soviet bombers appeared over Helsinki and Red Army divisions crossed the Finnish border along its whole length, from the Gulf of Finland to the Arctic Ocean. Few people outside Finland expected the fight to last long. The Soviet Union had about 170 million people. Finland had fewer than four million, a small air force and not much artillery ammunition. Moscow’s planners reportedly expected to reach Helsinki in about two weeks.
The war lasted 105 days. Finland lost territory, but it kept its independence, its democracy and its army. The Winter War became the founding story of modern Finland and one of the most studied underdog campaigns of the twentieth century. This guide explains why the war started, how the Finns fought it, how it ended and why it still matters in Finland today, including the country’s decision to join NATO in 2023.
Why the Winter War started
Finland had been independent only since 1917 (see our guide to Finnish Independence Day). For more than a century before that it was a Grand Duchy of the Russian Empire. Its border on the Karelian Isthmus lay only about 30 kilometres from Leningrad, the Soviet Union’s second city, and Stalin saw that as a threat.
In August 1939 the Soviet Union and Nazi Germany signed the Molotov–Ribbentrop Pact. A secret protocol divided Eastern Europe into spheres of influence, and Finland was placed in the Soviet one. That autumn Moscow pressured the three Baltic states into accepting Soviet military bases. It then made similar demands of Finland: move the border on the Karelian Isthmus back, hand over several islands in the Gulf of Finland, and lease the Hanko peninsula as a naval base. In return the Soviets offered a larger but much less valuable piece of forest in East Karelia.
The Finnish delegation, led by the veteran diplomat J. K. Paasikivi, was willing to make some concessions but would not give up the Isthmus defences or Hanko. Talks broke down in November. On 26 November the Soviets claimed that Finnish artillery had shelled the border village of Mainila. Historians now broadly agree that the incident was staged. Four days later the invasion began.
On 1 December Moscow announced a puppet “Finnish Democratic Republic” in the captured border town of Terijoki, headed by the exiled Finnish communist Otto Wille Kuusinen. The plan was to present the invasion as help for Finnish workers. It had the opposite effect. Only 21 years after a bitter civil war, Finns from right and left closed ranks.
How Finland fought back
Mannerheim and the Mannerheim Line
Finland’s commander-in-chief was Field Marshal Carl Gustaf Emil Mannerheim, then 72, a former officer in the Russian imperial army who had led the White side in 1918. The main defensive position across the Karelian Isthmus took his name. The Mannerheim Line was far less impressive than Soviet propaganda later claimed. It was mostly trenches, log bunkers, boulder tank traps and a small number of concrete strongpoints. It held because of the men in it, the forests and lakes around it, and Soviet tactics that sent infantry and tanks forward in poorly coordinated mass attacks.
Skis, snow and the motti
North of Lake Ladoga, the Red Army pushed whole divisions down narrow forest roads, aiming to cut Finland in half at its narrow “waist” near Oulu. The roads were the only routes through the wilderness, and the columns stretched for kilometres. Finnish ski troops in white snowsuits moved through the forest, cut the columns into isolated pockets and destroyed them one by one.
The Finns called these pockets motti, a word for a measured stack of firewood waiting to be chopped. The best-known example came at Suomussalmi and the Raate Road in December 1939 and January 1940, where two Soviet divisions were encircled and destroyed by a much smaller Finnish force. Weather helped the Finns. January 1940 was one of the coldest months of the century, with temperatures near −40°C. Finnish soldiers rotated through warm tents and saunas, while many Soviet troops had been sent north without winter clothing or skis. If you have read our piece on Finnish sauna culture, it may not surprise you that field saunas were built close to the front.
The Molotov cocktail
Finland had very few anti-tank guns, so its soldiers improvised. They used satchel charges, logs jammed into tank tracks, and bottles filled with a flammable mixture and lit with a rag or a storm match. Soviet foreign minister Vyacheslav Molotov claimed on the radio that Soviet planes were dropping food to starving Finns, not bombs. In response, Finns nicknamed the Soviet cluster bombs “Molotov’s bread baskets” and called their petrol bombs “a drink to go with the food”. The Molotov cocktail was not a Finnish invention, but the name is. Alko, the state alcohol monopoly, mass-produced the bottles during the war.
The White Death
Among the war’s legends is Simo Häyhä, a farmer and reservist from the Kollaa front, where the Finnish defence became so stubborn that “Kollaa holds” turned into a national catchphrase. Häyhä used a rifle with iron sights rather than a scope, partly because a scope lens could glint in the low winter sun. He is credited with around 500 kills, though historians disagree on the exact figure, and he was nicknamed “the White Death”. He was badly wounded in the face in March 1940, survived and lived until 2002.
The Nordic neighbours and the world
The invasion caused outrage abroad. On 14 December 1939 the League of Nations expelled the Soviet Union, its last significant act before the Second World War made it irrelevant. Britain and France talked about sending an expeditionary force, partly as a cover for seizing Swedish iron ore mines, but no troops arrived before the war ended.
Help from the Nordic neighbours was more concrete. Sweden stayed officially non-belligerent rather than neutral and sent weapons, money, aircraft and clothing. Around 8,000 Swedish volunteers went to fight under the slogan Finlands sak är vår (“Finland’s cause is ours”), and Swedish families took in thousands of Finnish children. Smaller groups of volunteers came from Norway and Denmark. This wartime solidarity is part of the background to the post-war cooperation described in our article on the Nordic Council and Passport Union. It also explains why Finns still take ties with Sweden seriously, a relationship covered in our guide to Finland’s Swedish speakers.
The February offensive and the Moscow Peace
The Soviet Union learned from its early failures. In January 1940 command passed to Semyon Timoshenko, who brought in more artillery, better coordination and fresh divisions. On 1 February he launched a huge offensive on the Karelian Isthmus. By mid-February the Red Army had broken through the main line at Summa, and the exhausted Finns fell back towards Viipuri (Vyborg), then Finland’s second-largest city.
With ammunition running out and no Western help arriving, the Finnish government negotiated. The Moscow Peace Treaty was signed on 12 March 1940, and the guns fell silent at 11 a.m. the next day. The terms were harsh. Finland gave up around a tenth of its territory, including most of Finnish Karelia, Viipuri and the shores of Lake Ladoga. It also had to lease Hanko to the Soviet Union. About 420,000 Karelians, roughly one in nine Finns, chose to leave their homes rather than live under Soviet rule. They were resettled across the rest of the country.
The human cost was severe on both sides. Around 25,000 Finns were killed. Soviet losses were far higher. Russian archival figures put them at more than 126,000 dead, and many historians think the true number was larger.
What happened next
The Winter War was only the first chapter. In June 1941, hoping to recover its lost land, Finland joined Germany’s attack on the Soviet Union in what Finns call the Continuation War. That war ended in 1944 with a second armistice and further losses, followed by the Lapland War against German forces in the north. Our Finnish Lapland travel guide explains why towns such as Rovaniemi look so modern: they were largely burned during the German retreat. Through all of it, Finland was never occupied and kept its parliamentary democracy, which few countries on the continent’s eastern front managed.
Why the Winter War still matters in Finland
The “spirit of the Winter War”
Finns still talk about talvisodan henki, the spirit of the Winter War. It describes the national unity that bridged the wounds of 1918 and the idea that a small nation can survive if everyone pulls together. It is closely linked to sisu, the Finnish idea of stubborn inner strength, and the war is often given as the best example of sisu in action.
Defence, shelters and NATO
The war’s lessons shaped Finnish policy for decades. Finland kept a large conscript reserve, built thousands of civil defence shelters (Helsinki has enough shelter space for its whole population, some of it used in peacetime as sports halls and car parks) and developed a “comprehensive security” model that involves the whole of society. During the Cold War it stayed militarily non-aligned and careful in its dealings with Moscow. After Russia’s full-scale invasion of Ukraine in 2022, Finnish public opinion changed quickly, and Finland joined NATO on 4 April 2023. Commentators in Finland and abroad drew direct comparisons with 1939.
Culture and memory
The war runs through Finnish culture, from the 1989 film Talvisota to family stories about lost Karelian homes. Karelian dishes such as the rye-crusted karjalanpiirakka pie, brought west by evacuees, are now eaten across the country. Even Finland’s national composer is part of the story, since Sibelius’s music was broadcast as a symbol of resistance (read more in our profile of Jean Sibelius).
Where to learn more on a trip to Finland
- Helsinki: the Finnish Military Museum covers the wars of independence and the Second World War. The city’s war memorials and cemeteries, including Hietaniemi, where Mannerheim is buried, are easy to fit into a city break. Our Helsinki city guide has more ideas.
- Suomussalmi and the Raate Road: in the Kainuu region, the Raate Road memorial site has a museum and a moving monument to the fallen of both sides. It is remote but rewarding on a road trip through eastern Finland.
- The eastern border region: trenches, bunkers and memorials are scattered through the forests of North Karelia and the southeast. Many are signposted walking sites.
Opening hours at smaller museums can be seasonal, so check before you travel.
Conclusion
The Winter War lasted just over three months, and Finland did not win it in the usual sense. It lost a tenth of its land and one of its main cities. But it achieved what mattered most: it stayed free. The image of ski troops in white snowsuits holding back an army many times their size has become part of how Finns see themselves, and that memory still shapes Finland’s defence policy, its relations with its neighbours and its sense of sisu.
