Winter War (1939–1940): Finland's Stand Against the Soviets

The Winter War was the conflict between the Soviet Union and Finland from 30 November 1939 to 13 March 1940. Stalin expected a quick victory, but the much smaller Finnish army held out for more than three months in a bitter winter, inflicting heavy losses before Finland accepted harsh peace terms. The war preserved Finnish independence, damaged the Red Army’s reputation and shaped decisions across Europe in the following year.

Background: Leningrad and the secret protocol

Finland had been a grand duchy of the Russian Empire until it declared independence in December 1917. The border on the Karelian Isthmus lay only about 32 kilometres from Leningrad, the Soviet Union’s second city, which Soviet leaders regarded as a strategic danger. The secret protocol of the Molotov-Ribbentrop Pact of August 1939 placed Finland in the Soviet sphere of influence, the same agreement that led to the Soviet invasion of Poland in September.

In October 1939, after pressing the Baltic states into accepting Soviet bases, Moscow summoned Finnish negotiators led by J. K. Paasikivi. Stalin demanded that the border on the isthmus be moved westwards, that Finland cede several islands in the Gulf of Finland and that it lease the Hanko peninsula for a naval base. In return he offered a larger but less valuable area of Soviet Karelia. Finland offered partial concessions but refused to give up Hanko or its main defences, and talks broke down in November.

The invasion

On 26 November 1939 the Soviet Union claimed that Finnish artillery had shelled the village of Mainila, killing Soviet soldiers. Historians agree that the incident was staged by the Soviet side. Moscow renounced its non-aggression treaty with Finland, and on 30 November the Red Army attacked along the whole border while aircraft bombed Helsinki.

The next day the Soviet Union set up a puppet “Finnish Democratic Republic” at Terijoki under the exiled Finnish communist Otto Wille Kuusinen, and claimed to recognise it as the legitimate government. Instead of dividing the country, the invasion united Finns across the political divisions left by the civil war of 1918. On 14 December the League of Nations expelled the Soviet Union.

Finnish resistance

Finland mobilised around 300,000 men under Marshal Carl Gustaf Emil Mannerheim, against an initial Soviet force of about 450,000 that grew much larger during the war. The Finns had few tanks, little artillery ammunition and a small air force. They did have soldiers used to the forests and the cold, who moved quickly on skis in white camouflage.

On the Karelian Isthmus Soviet attacks in December were stopped at the Mannerheim Line, a belt of trenches, obstacles and bunkers. Further north, Soviet divisions advanced along a few narrow forest roads. At Suomussalmi in December and January Finnish forces under Colonel Hjalmar Siilasvuo cut the Soviet 163rd and 44th Divisions into isolated pockets, which the Finns called motti, and destroyed them one by one. Victories at Tolvajärvi and the long defence at Kollaa became national symbols.

Finnish soldiers used improvised petrol bombs against Soviet tanks and named them Molotov cocktails, mocking the Soviet foreign minister. Sniper Simo Häyhä became one of the most famous soldiers of the war, credited with several hundred kills, although exact figures are uncertain.

Key people

• Carl Gustaf Emil Mannerheim, a former officer of the Russian imperial army and victor of the Finnish Civil War, was recalled at the age of 72 to command the Finnish forces. His calm leadership made him a national symbol.
• Joseph Stalin approved the attack and, like most Soviet planners, expected a short campaign that would be over within a few weeks.
• Semyon Timoshenko took command of the Soviet forces on the Karelian Isthmus in January 1940 and organised the methodical offensive that broke the Finnish line.
• Risto Ryti became Finnish prime minister in December 1939 and led the government that negotiated peace.
• Otto Wille Kuusinen, a Finnish communist who had lived in Soviet exile since 1918, headed the short-lived puppet government at Terijoki, which Moscow quietly dropped when it opened talks with Helsinki.

The Soviet breakthrough and peace

The failures of December led to a Soviet reorganisation under Semyon Timoshenko. Fresh divisions, heavy artillery and tanks were concentrated on the isthmus, and the main offensive began in early February 1940. After days of intense bombardment the Red Army broke through near Summa around 11 to 15 February, forcing the Finns back towards Viipuri.

Britain and France discussed sending an expedition to help Finland, partly to seize the Swedish iron ore fields on the way, but Norway and Sweden refused transit and the plans came to nothing. Some 8,000 Swedish volunteers and smaller groups from other countries did fight for Finland. With its army exhausted, the Finnish government of Risto Ryti agreed to talks, and the Moscow Peace Treaty was signed on 12 March 1940. Fighting ended at 11 am Finnish time the next day.

Consequences

Finland ceded about a tenth of its territory, including the Karelian Isthmus, Viipuri, the region north of Lake Ladoga, part of Salla and part of the Rybachy peninsula, and leased Hanko for 30 years. More than 400,000 Karelians, about 12 per cent of the population, were evacuated and resettled elsewhere in Finland. Almost all chose to leave rather than live under Soviet rule, and their resettlement, with land taken partly from existing farms, was one of the great social tasks of the following years.

Abroad, the war won Finland wide sympathy. Newspapers in Britain, France, Sweden and the United States praised the small democracy standing up to a dictatorship, and money, weapons and volunteers were collected in many countries. Yet the help that arrived was too little and too late to change the military balance, a lesson Finnish leaders did not forget when they looked for support in 1940 and 1941.

The Red Army’s poor performance, partly a result of Stalin’s purges of the officer corps, encouraged Hitler to underestimate Soviet strength. The Soviet Union reformed its training and command, lessons that mattered after Operation Barbarossa. Seeking to regain its lost lands, Finland fought alongside Germany against the Soviet Union in the Continuation War from June 1941 to September 1944.

Myths and facts

Myth: the Mannerheim Line was a Finnish equivalent of the Maginot Line. It was mostly field fortifications with only a limited number of concrete strongpoints. Soviet accounts exaggerated its strength to explain their early failures.

Myth: Finland won the Winter War. Finland lost significant territory and could not have held out much longer. Its real achievement was avoiding occupation, which Estonia, Latvia and Lithuania suffered in 1940.

By the numbers

Timeline

• 1939, 12 October: Soviet-Finnish negotiations open in Moscow.
• 1939, 26 November: The staged Mainila shelling gives the Soviet Union a pretext.
• 1939, 30 November: The Red Army invades Finland and Helsinki is bombed.
• 1939, 14 December: The League of Nations expels the Soviet Union.
• 1940, 8 January: Finnish forces complete the destruction of the Soviet 44th Division on the Raate road near Suomussalmi.
• 1940, 1 February: The major Soviet offensive on the Karelian Isthmus begins.
• 1940, 12 March: The Moscow Peace Treaty is signed.
• 1940, 13 March: Fighting ends at 11 am.

Why it matters

The Winter War showed that a small, determined nation could resist a great power, at least for a time, and it remains central to Finnish national memory. It also exposed the weakness of the Red Army in 1939, influenced German planning for the invasion of the Soviet Union, and was linked to Allied interest in Scandinavia that preceded the German invasion of Norway.