The 'Winter War', also known as the '1^st Soviet-Finnish War' and to the Finns as the 'Talvisota', was fought between the USSR and Finland (30 November 1939/13 March 1940).

The war began with a Soviet invasion of Finland on 30 November 1939, three months after the outbreak of World War II, and ended three and a half months later with the Moscow Peace Treaty on 13 March 1940. Despite its greatly superior military strength, especially in tanks and aircraft, the USSR suffered severe losses and initially made little headway even as the League of Nations deemed the attack illegal and expelled the USSR from the organisation.

The Soviets made several demands, including that Finland cede substantial border territories in exchange for land elsewhere, claiming security reasons based primarily on the protection of Leningrad, 20 miles (32 km) from the Finnish border. When Finland refused, the Soviets invaded. Most sources conclude that the USSR had intended to take Finand in its entirety, and to use the establishment of the puppet Finnish communist government and the Molotov-Ribbentrop Pact’s secret protocols as evidence of this, while some sources argue against the idea of a full Soviet conquest. Finland repelled the Soviet attacks for more than two months and inflicted substantial losses on the invaders while temperatures fell as low as -43° C (-45° F). The battles focused mainly on Taipale along the Karelian isthmus, on Kollaa in Ladoga Karelia and on the Raate road in Kainuu, but there were also battles in Salla and Petsamo in Lapland. After the Soviet military had reorganised and adopted different tactics, they renewed their offensive in February and overcame the Finnish defences.

Hostilities ceased in March 1940 with the signing of the Moscow Peace Treaty, in which Finland ceded 9% of its territory to the USSR. The Soviet losses were heavy, and the country’s international reputation suffered. The Soviet gains exceeded the Soviet pre-war demands, and the Soviets received substantial territories along Lake Ladoga and farther to the north. Finland retained its sovereignty and enhanced its international reputation. Moreover, the poor performance of the Soviet army encouraged the German leader, Adolf, Hitler to believe that an attack on the USSR would be successful and confirmed negative Western opinions of the Soviet military. After 15 months of interim peace, in June 1941 Germany launched 'Barbarossa', and the 'Continuation War' ('Jatkosota') between Finland and the USSR began.

Until a time early in 19^th 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, St Petersburg, and eventually led to the conquest and annexation of Finland and its conversion into an autonomous buffer state. The resulting Grand Duchy of Finland enjoyed wide autonomy within Russia until the end of the 19^th century, when Russia began attempts to assimilate Finland as part of a general policy to strengthen the central government and unify the empire by mens of Russification. Those attempts were aborted because of Russia’s internal strife, but ruined Russia’s relations with Finland and increased support for Finnish self-determination movements.

World War I led to the collapse of the Russian empire during the revolutions of 1917 and thereby paved the way to the Russian Civil War. On 15 November 1917, the Bolshevik government 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 declared the nation’s independence. Soviet Russia, later the USSR, recognised the new Finnish government just three weeks after the declaration. Finland achieved full sovereignty in May 1918 after a four-month civil war in which the conservative Whites defeated the socialist Reds with the help of the Imperial German army, pro-German Jäger elements and some Swedish troops, and in addition led to the expulsion of Bolshevik troops.

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 such as, for example, the joint defence of the Åland isand group), rather than on military exercises or on the stockpiling and the deployment of matériel. Nevertheless, Sweden carefully avoided committing itself to Finnish foreign policy. Finland’s military policy included clandestine defence co-operation with Estonia.

The period after the Finnish Civil War until the early 1930s was a politically unstable time in Finland as a result 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 anti-communist violence, which culminated in a failed coup attempt in 1932. The successor of the Lapua Movement, the 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. By a time late in the 1930s, the export-oriented Finnish economy was growing and the nation’s extreme political movements had diminished.

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, namely the Viena and Aunus expeditions, 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 commander-in-chief, Kenraali C. G. E. Mannerheim. On 14 October 1920, Finland and Soviet Russia signed the 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. Despite the signature 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 in Russia during 1921, and Finnish communists in the USSR continued to prepare for revenge and staged a cross-border raid into Finland, the Pork Mutiny, in 1922. In 1932, the Soviet-Finnish Non-Aggression Pact was signed between both countries, and thus was reaffirmed for 10 years in 1934. Foreign trade in Finland was booming, but less than 1% of it was with the USSR. In 1934, the USSR also joined the League of Nations.

Soviet General Secretary Iosef Stalin was disappointed by Soviet Russia’s failure to halt the Finnish Revolution. He thought that the pro-Finland movement in Karelia posed a direct threat to Leningrad and that the area and defences of Finland could be used to invade the Soviet Union and/or restrict naval movements. Soviet propaganda then painted Finland’s leadership as a 'vicious and reactionary fascist clique'. Mannerheim and Väinö Tanner, the leader of the Finnish Social Democratic Party, were targeted for particular scorn. When Stalin gained absolute power through the great purge of 1938/39, the Soviets changed their foreign policy toward Finland and began to pursue the reconquest of the provinces of tsarist Russia which had been lost during the chaos of the October Revolution of 1917 and the subsequent Russian Civil War. Soviet leaders believed that the old empire’s extended borders provided territorial security and wished Leningrad (ex-St Petersburg) to enjoy a similar level of security against the rising power of Nazi Germany.

In April 1938, Boris Yartsev, an agent of thre NKVD, contacted Aimto Cajander and Rudolf Holsti, the Finnish prime minster and foreign minister respectively, to state that the USSR did not trust Germany and that war between the two countries was considered possible. The Soviet army would not wait passively behind the border but would instead 'advance to meet the enemy'. Finnish representatives assured Yartsev that Finland was committed to a policy of neutrality and that the country would resist any armed incursion. Yartsev suggested that Finland cede or lease some islands in the Gulf of Finland along the seaward approaches to Leningrad, but Finland refused. Negotiations continued throughout 1938 without result. The Finnish reception of Soviet entreaties was decidedly cool, as the violent collectivisation and purges in Stalin’s USSR had drastically powered Finland’s opinion of the USSR. Most of the Finnish communist elite in the USSR had been executed during the 'great purge', further tarnishing the Soviets' image in Finland. Meanwhile, Finland was attempting to negotiate a military co-operation plan with Sweden and hoping to jointly defend the Åland islands group.

The USSR and Germany signed the Molotov-Ribbentrop Pact in August 1939. It was publicly a non-aggression treaty, but it included a secret protocol in which eastern European countries were divided into spheres of German and Soviet interest. Finland fell into the Soviet sphere. On 1 September 1939, Germany began its 'Weiss' (i) invasion of Poland, and two days later the UK and France declared war on Germany. On 17 September, the Soviets invaded eastern Poland. Estonia, Latvia and Lithuania were soon forced to accept treaties that allowed the Soviets to establish military bases on their soil: Estonia accepted the ultimatum by signing the agreement on 28 September, and Latvia and Lithuania followed in October. Unlike the three Baltic countries, Finland started a gradual mobilisation under the guise of 'additional refresher training'. The Soviets had already started intensive mobilisation near the Finnish border in 1938/39. Assault troops thought to be necessary for the invasion did not begin deployment until October 1939, and operational plans made in September called for the invasion to start in November.

On 5 October 1939, the Soviets invited a Finnish delegation to Moscow for negotiations, and Juho Kusti Paasikivi, the Finnish envoy to Sweden, was sent to Moscow to represent the Finnish government. The Soviet delegation demanded that the border between the USSR and Finland on the Karelian isthmus be moved westward to a point only 18.5 miles (30 km) to the east of Viipuri (Vyborg in Russian) and that Finland destroy all existing fortifications on the Karelian isthmus. Likewise, the Soviet delegation demanded the cession of islands in the Gulf of Finland as well as the Rybachy peninsula (Kalastajasaarento in Finnish). The Finns would also have to lease the Hanko peninsula, in south-western Finland on the northern side of the entrance to the Gulf of Finland for 30 years and to permit the Soviets to establish a military base there. In exchange, the USSR would cede Repola and Porajärvi from Eastern Karelia, an area twice the size as that of the territory demanded from Finland.

The Soviet offer divided the Finnish government, but was eventually rejected as a result of a decidedly adverse reaction by the Finnish public and parliament. On 31 October, Vyacheslav Molotov, the Soviet foreign minister, publicly announced the Soviet demands to the Supreme Soviet. The Finns made two counter-offers to cede the Terijoki area to the USSR, which would double the distance between Leningrad and the Finnish border, but this was far less than the Soviets had demanded. The Finns also offered to cede the islands in the Gulf of Finland. The Finnish delegation returned home on 13 November and took for granted that the negotiations would continue.

On 26 November 1939, an incident was reported near the Soviet village of Mainila, near the border with Finland. A Soviet border guard post had been shelled by an unknown party resulting, according to Soviet reports, in the deaths of four border guards and injuries to another nine. Research conducted by several Finnish and Russian historians later concluded that the shelling was a 'false flag' operation since there were no artillery units there, and had been carried out from the Soviet side of the border by an NKVD unit with the purpose of providing the Soviets with a casus belli and a pretext to withdraw from the non-aggression pact. Soviet war games in March 1938 and 1939 had been based on a scenario in which border incidents taking place at the village of Mainila would spark the war.

Molotov claimed that the incident was a Finnish artillery attack, and demanded that Finland apologise for the incident and move its forces beyond a line 12.5 to 16 miles (20 to 25 km) from the border. Finland denied responsibility for the attack, rejected the demands and called for a joint Finnish and Soviet commission to examine the incident. In turn, the USSR claimed that the Finnish response was hostile, renounced the non-aggression pact and severed diplomatic relations with Finland on 28 November. In the following years, Soviet historiography described the incident as Finnish provocation. Doubt was cast on the the Soviet official version was cast only late in the 1980s during the policy of glasnost (openness).

Before the war, the Soviet leadership had expected total victory within a few weeks. The Soviet army had just completed its invasion of eastern Poland at a cost of fewer than 4,000 casualties after Germany had attacked Poland from the west. Stalin’s expectations of a quick Soviet triumph were backed up by the politician Andrei A. Zhdanov and the military strategist Marshal Sovetskogo Soyuza Kliment Ye. Voroshilov, but other generals were more reserved. The Soviet army’s chief-of-staff, Komandarm 1^st Rank Boris M. Shaposhnikov advocated a larger build-up, extensive fire support and logistical preparations, a rational order of battle and the deployment of the army’s best units. Zhdanov’s military commander, Meretskov, reported that 'the terrain of coming operations is split by lakes, rivers, swamps, and is almost entirely covered by forests…The proper use of our forces will be difficult.' These doubts were not reflected in Meretskov’s troop deployments, and he publicly announced that the Finnish campaign would take two weeks at most. Soviet soldiers had even been warned not to cross the border mistakenly into Sweden. Zhdanov, the leader of the Leningrad Military District, commissioned a celebratory piece of music from Dmitri Shostakovich, the Suite on Finnish Themes to be performed as the marching bands of the Soviet army paraded through Helsinki.

Stalin’s purges of 1938/39 had devastated the Soviet army’s officer corps, however. Those purged included three of its five marshals, 220 of its 264 divisional or higher-level commanders, and 36,761 officers of all ranks. Fewer than half of all the officers remained, and these were commonly replaced by soldiers who were less competent but more loyal to their superiors. Unit commanders were overseen by political commissars, whose approval was needed to approve and ratify military decisions, which they evaluated based on their political merits. The dual system further complicated the Soviet chain of command and effectively removed the independence of commanding officers.

After the Soviet success at the Battles of Khalkhin Gol against Japan, on the USSR’s eastern border, the Soviet high command had divided into two factions. One of these was represented by the Spanish Civil War veterans Komkor Pavel V. Rychagov from the Soviet air forces, the tank expert Komkor Dmitri F. Pavlov and Stalin’s favourite general, Komanarm 1^st rank Grigori I. Kulik, the chief of artillery; and the other was led by Khalkhin Gol veterans Komkor Georgi K. Zhukov of the army and Kombrig Grigori P. Kravchenko of the air forces. Under this divided command structure, the lessons of the USSR’s 'first real war on a massive scale using tanks, artillery, and aircraft' at Khalkin Gol went unheeded. As a result, the Soviet forces' BT light tanks were less successful during the 'Winter War', and it took the USSR three months and the loss of more than 1 million men to accomplish what Zhukov had managed at Khalkhin Gol in 10 days, albeit in completely different circumstances.

Soviet generals were impressed by the success of Germany’s innovatory Blitzkrieg tactics, but these had been tailored to conditions in Central Europe, with its dense well-mapped network of paved roads. Armies fighting there had recognised supply and communications centres, which could be easily targeted by armoured vehicle regiments. Finnish army centres, however. were deep inside the country. There were no paved roads, and even gravel or dirt roads were scarce. Most of the terrain consisted of trackless forests and swamps. The waging of Blitzkrieg in Finland was a highly difficult proposition, though, and the Soviet army signally failed to meet the level of tactical co-ordination and local initiative that would be required to execute such tactics in Finland.

Meretskov, the commander of the Leningrad Military District, initially commanded the overall operation against the Finns, but on 9 December the command was passed to the General Staff Supreme Command (later known as the Stavka), directly under Voroshilov (chairman), Admiral Nikolai G. Kuznetsov, Stalin and Komandarm 1-ranga Boris M. Shaposhnikov, the chief of the general staff. In January 1940 the Leningrad Military District was re-formed as the North-Western Front with Komandarm 1-ranga Semyon K. Timoshenko as commander-in-chief and orders to break the 'Mannerheim Line'.

The Soviet forces were organised with Komandarm 2-ranga Vsevolod F. Yakovlev’s 7^th Army (later divided into the 7^th Army and 13^th Army), comprising nine divisions, one tank corps and three tank brigades on the Karelian isthmus with the city of Viipuri as its objective was the city of Viipuri; Komdiv Ivan N. Khabarov’s 8^th Army, comprising six divisions and one tank brigade, to the north of Lake Ladoga with the task of executing a flanking manoeuvre around the northern shore of Lake Ladoga to strike at the rear of the 'Mannerheim Line'; Komkor Mikhail P. Dhukanov’s 9^th Army, comprising three divisions wit one more division on its way to the formation, was to strike into central Finland through the Kainuu region and thrust to the west in order to cut Finland in two; and Komkor Valerian A. Frolov’s 14^th Army, comprising three divisions, in Murmansk with the objectives of taking the Arctic port of Petsamo and then advancing on Rovaniemi.

On the other side of the front, the Finnish strategy was dictated by geography. The 830-mile (1340-km) frontier with the USSR was largely impassable except along a handful of unpaved roads. In pre-war calculations, the Finnish defence command, which had established its wartime headquarters at Mikkeli, had estimated that there were seven Soviet divisions on the Karelian isthmus and no more than five along the whole border to the north of Lake Ladoga. In this estimation, the manpower ratio would have favoured the attacker by 3/1, but the true ratio was considerably higher, however as, for example, there were 12 Soviet divisions deployed to the area north of Lake Ladoga.

Finland had a large force of reservists, who were trained in regular manoeuvres and of which some had combat experience from the recent Finnish Civil War. The soldiers were also almost universally trained in basic survival techniques, such as skiing. The Finnish army was not able to equip all its men with proper uniforms at the outbreak of war, but its reservists were equipped with warm civilian clothing. However, the sparsely populated and highly agrarian Finland had to draft so many of its working men that the Finnish economy was massively strained by the resulting shortage of workers. An even greater problem than lack of soldiers was the lack of matériel since foreign shipments of anti-tank weapons and aircraft were arriving only in small quantities. The ammunition situation was alarming, as stockpiles had cartridges, shells and fuel to last only 19 to 60 days. The ammunition shortage meant the Finns could seldom afford counter-battery or saturation fire. The Finnish tank force was operationally non-existent. The ammunition situation was alleviated somewhat since the Finns were armed primarily with Mosin-Nagant rifles dating from the Finnish Civil War, which used the same cartridge as that used by Soviet forces. The situation was so severe that Finnish soldiers sometimes had to maintain their ammunition supply by stripping the bodies of dead Soviet soldiers.

Kenraaliluutnantti Hugh Victor Österman’s Kannaksen Armeija (Army of the Isthmus) comprised six divisions deployed in two corps. Kenraaliluutnantii Harald Öhquist’s II Armeijakunta (from right to left the 4^th Divisioona, 5^th Divisioona, 11^th Divisioona and Ratsuväkiprikaati [cavalry brigade]) positioned on the Finnish right, and Kenraalimajuri Erik Heinrichs’s III Armeijakunta (right to left the 8^th Divisioona and 10^th Divisioona) on the left flank. In army reserve, the 1^st Divisioona was deployed to the rear of the junction of the II Armeijakunta and III Armeijakunta.

It was these forces which were responsible for the defence of the 'Mannerheim Line' ('Mannerheim-linja'), which was a the line of defensive fortifications on the Karelian isthmus built by Finland against the threat of Soviet invasion. While this defensive line was never allocated an official name, during the 'Winter War' it became known as the 'Mannerheim-linja'. The defences had been constructed in two phases during 1920/24 and 1932/39, and by November 1939, when the 'Winter War' began, the line was by no means complete.

Immediately behind the border on the isthmus front were four delaying groups named after their locations, from south to north, at Uusikirkko, Muolaa, Lipola and Rautu.

(On 25 February the II Armeijajunta was divided and a new I Armeijakunta was established under the command of Kenraalimajuri Taavetti Laatikainen with the 1^st Divisioona and the 2^nd Divisioona, as the 11^th Divisioona had been redesignated.)

In the area to the north of the isthmus, the IV Armeijakunta was located to the north of Lake Ladoga with two divisions under the command of Kenraalimajuri Juho Heiskanen, who was soon replaced by Kenrallimajuri Woldemar Hägglund, and the Ryhmä 'Pohjois-Suomen' (North Finland Group), which was a collection of White Guards, border guards and drafted reservist units under the command of Kenraalimajuri Viljo Tuompo.

On 30 November 1939, the USSR invaded Finland with 21 divisions, totalling 450,000 men, and bombed Helsinki, where about 100 civilians were killed and more than 50 buildings were destroyed. In response to international criticism, the Soviet foreign minister, Molotov, stated that the Soviet air forces were not bombing Finnish cities but rather dropping humanitarian aid to the starving Finnish population. The Finnish statesman J. K. Paasikivi commented that the Soviet attack without a declaration of war violated three separate non-aggression pacts: the Treaty of Tartu, which had been signed in 1920; the non-aggression pact between Finland and the USSR, which had been signed in 1932 and again in 1934; and also the Covenant of the League of Nations, which the USSR signed in 1934. Mannerheim was appointed commander-in-chief of the Finnish forces after the Soviet attack. In a further reshuffling, Aimo Cajander’s caretaker cabinet was replaced by Risto Ryti and his cabinet, with Väinö Tanner as foreign minister because of opposition to Cajander’s pre-war politics. Finland brought the matter of the Soviet invasion before the League of Nations, which expelled the USSR on 14 December 1939 and exhorted its members to aid Finland.

On 1 December 1939, the USSR created a puppet government, named the Finnish Democratic Republic, to govern Finland after the Soviets had taken the country. Headed by Otto Wille Kuusinen, the puppet government operated in the parts of Finnish Karelia occupied by the Soviets, and was also known as the 'Terijoki Government' after the village of Terijoki, the first settlement captured by the Soviet advance. After the war, the puppet government was reabsorbed into the USSR. From the very outset of the war, the vast majority of working-class Finns stood behind the legitimate government in Helsinki, and the Finnish national unity against the Soviet invasion later came to be called the 'Spirit of the Winter War'.

The complex of Finnish defence structures that during the war became known as the 'Mannerheim-linja' was located across the Karelian isthmus approximately 18.5 to 47 miles (30 to 75 km) from the Soviet border. The Soviet troops on the isthmus totalled some 250,000 men facing 130,000 Finnish troops. The Finnish command deployed a defence in depth of about 21,000 men in the area in front of the 'Mannerheim-linja' to delay and damage the Soviet forces before they reached the line. In combat, the most severe cause of confusion among the Finns was Soviet armour, for the Finns possessed few anti-tank weapons and had insufficient training in modern anti-tank tactics. The favoured Soviet armoured tactic was a simple frontal charge, the weaknesses of which could be exploited. The Finns quickly earned that, at close range, tanks could be dealt with in many ways: for example, logs or crowbars jammed into the bogie wheels would often immobilise a tank. The Finns soon fielded a better improved weapon, the so-called 'Molotov cocktail', a glass bottle filled with flammable liquids and fitted with a simple hand-lit fuse. Molotov cocktails were eventually mass-produced by the Alko alcoholic beverage corporation and bundled with matches with which to light them. 80 Soviet tanks were destroyed in the border zone engagements.

By 6 December, the four Finnish covering groups had withdrawn to the 'Mannerheim-linja'. The Soviet forces began their first major attack against the line in the Taipale area between the shore of Lake Ladoga, the Taipale river and the Suvanto waterway. Along the Suvanto sector, the Finns had a slight advantage of higher ground and dry ground into which to dig. The Finnish artillery had scouted the area and made fire plans in advance, anticipating a Soviet assault. The 'Battle of Taipale' opened with a 40-hour Soviet artillery preparation. After the barrage, Soviet infantry attacked across open ground but was repulsed with heavy casualties. From 6 to 12 December, the Soviets continued their effort using just one division. Next, the Soviets strengthened their artillery and deployed tanks and the 150^th Division forward to the Taipale front. On 14 December, the boosted Soviet forces launched a new attack but were pushed back again. A third Soviet division entered the fight but performed poorly and panicked under artillery fire. The assaults continued without success, and the Soviets suffered heavy losses. One typical Soviet attack during the battle lasted just an hour but left 1,000 dead and 27 tanks strewn on the ice. To the north of Lake Ladoga, on the Ladoga Karelia front, the defending Finnish units relied on the terrain. Ladoga Karelia, which was a large forest wilderness, lacked any form of road network which the modern Soviet forces could exploit. The 8^th Army had extended a new railway line to the border, and this could double the front’s supply capability. On 12 December, the advancing 139^th Division, supported by the 56^th Division, was defeated by a much smaller Finnish force under Talvela in the 'Battle of Tolvajärvi', the first Finnish victory of the war.

In central and northern Finland, the roads were few in number and poor in quality, and the terrain hostile. The Finns expected no major Soviet attacks, but the Soviets in fact committed eight divisions, heavily supported by armour and artillery. The 155^th Division attacked at Lieksa, and farther to the north the 44^th Division attacked at Kuhmo. The 163^rd Division was deployed at Suomussalmi and ordered to cut Finland in half by advancing on the Raate road. In Finnish Lapland, the 88^th Division and 122^nd Division attacked at Salla. The Arctic port of Petsamo was attacked by the 104^th Mountain Division by sea and land, supported by naval gunfire.

The winter of 1939/40 was exceptionally cold, with the Karelian isthmus experiencing a record low temperature of -43° C (-45° F) on 16 January 1940. At the beginning of the war, only those Finnish soldiers who were in active service had uniforms and weapons. The rest had to make do with their own clothing, which for many soldiers was their normal winter clothing with a semblance of insignia added. Finnish soldiers were generally skilled in cross-country skiing, and the cold, snow, forest and long hours of darkness were all factors which the Finns could use to their advantage. The Finns dressed in layers, and the ski troops wore a lightweight white snow cape. This snow camouflage rendered the ski troops almost invisible so that they could more easily execute guerrilla attacks against Soviet columns. At the beginning of the war, Soviet tanks were painted in standard olive drab and men dressed in regular khaki uniforms, and it was not until a time late in January 1940 that the Soviets started to paint their equipment white and issue snowsuits to their infantry. Most Soviet soldiers had proper winter clothing, but this was not the case with every unit: in the 'Battle of Suomussalmi', thousands of Soviet soldiers died of frostbite. The Soviet troops also lacked skill in skiing, so soldiers were restricted to movement by road and were forced to move in long columns. The Soviet troops lacked proper winter tents, and the men had therefore to sleep in improvised shelters. Some Soviet units incurred frostbite casualties as high as 10% even before crossing the Finnish border. However, the cold weather did give an advantage to Soviet tanks as they could move over frozen terrain and bodies of water, rather than being immobilised in swamps and mud. It had been estimated that at least 61,506 Soviet troops were sick or frostbitten during the war.

In fighting between Ladoga Karelia to the Arctic port of Petsamo, the Finns made extensive use of guerrilla tactics. The Soviets were superior in numbers and matériel, but the Finns exploited the advantages of speed, manoeuvre warfare and economy of force. Particularly on the Ladoga Karelia front and during the 'Battle of the Raate Road', the Finns isolated portions of the numerically superior Soviet forces and, with the Soviet forces divided into smaller groups, the Finns dealt with them individually with attacks from all sides.

For many of the Soviet troops encircled in a pocket (called a motti in Finnish), remaining alive was an ordeal comparable to combat. The men were freezing and starving, and endured poor sanitary conditions. As one historian had put it: 'The Soviet soldier had no choice. If he refused to fight, he would be shot. If he tried to sneak through the forest, he would freeze to death. And surrender was no option for him; Soviet propaganda had told him how the Finns would torture prisoners to death.' The problem for the Finns, however, lay in the fact that they were mostly too weak in numerical terms for a full exploitation of their tactical successes. Some of the mottis of encircled Soviet soldiers held out for weeks and even months, thereby pinning larger numbers of Finnish troops.

The terrain on the Karelian isthmus did not allow guerrilla tactics, so the Finns were forced to resort to the more conventional defences of the 'Mannerheim-linja', with its flanks protected by large bodies of water. Soviet propaganda claimed that the Finnish defensive line was as strong as or even stronger than the 'Ligne Maginot', but Finnish historians have belittled the line’s strength, insisting that it comprised, for the most part, conventional trenches and log-covered dug-outs. The Finns had built 221 strongpoints across the Karelian isthmus, most of them in the early 1920s, and many were extended in the late 1930s. Despite these defensive preparations, even the most heavily fortified section of the 'Mannerheim-linja' had only one reinforced-concrete bunker per kilometre. In overall terms, the line was weaker than similar lines in mainland Europe. According to the Finns, the real strength of the line was the 'stubborn defenders with a lot of sisu', a Finnish idiom translatable as 'guts' or 'fighting spirit'.

On the north-eastern side of the isthmus, the Soviets tried to break through the 'Mannerheim-linja' in the 'Battle of Taipale', and on the south-western side Soviet units faced the Finnish line at Summa, near the city of Viipuri, on 16 December. The Finns had built 41 reinforced-concrete bunkers in the Summa area, making the defensive line in this area stronger than anywhere else on the Karelian isthmus. Because of a mistake in planning, however, the nearby Munasuo swamp had a 0.6-mile (1-km) gap in the line. During the '1^st Battle of Summa', a number of Soviet tanks broke through the thin line on 19 December, but the Soviets were then unable to benefit from the situation for lack of adequate co-operation between branches of service. The Finns remained in their trenches, allowing the Soviet tanks to move freely behind the Finnish line, as the Finns had no proper anti-tank weapons, but the Finns succeeded in repelling the main Soviet assault. The tanks, stranded behind the Finnish lines, attacked the strongpoints at random until all 20 of them were eventually destroyed. By 22 December, the battle had come to an end in Finnish victory.

The Soviet advance was stopped on the 'Mannerheim-linja'. Suffering from poor morale and a shortage of supplies, Soviet troops eventually refusing to participate in more suicidal frontal attacks. Öhquist’s decoded to commit his Finnish troops in a counterattack to encircle three Soviet divisions in a motti near Viipuri on 23 December, but this bold plan failed. The Finns lost 1,300 men, and the Soviets were later estimated to have lost a similar number.

The Soviet strength in the area to the north of Lake Ladoga in Ladoga Karelia surprised the Finnish headquarters. The two Finnish divisions deployed in this region were Eversti Lauri Tiainen’s 12^th Divisioona and Eversti Hannu Hannuksela’s 13^th Divisioona, and these were supported by three brigades, bringing their total strength to more than 30,000 men. The Soviets deployed one division one almost every road leading westward to the Finnish border. The 8^th Army was commanded initially by Khabarov, who was replaced by Komandarm 2-ranga Grigori M. Shtern on 13 December. The Soviet forces' mission was to destroy the Finnish troops in the Ladoga Karelia region and advance into the area between Sortavala and Joensuu within 10 days. The Soviets had a 3/1 advantage in manpower and a 5/1 advantage in artillery, as well as air supremacy.

The Finnish forces at first panicked and retreated in front of the overwhelming Soviet strength. Heiskanen, the commander of the IV Armeijakunta, was therefore replaced by Hägglund on 4 December. On 7 December, in the middle of the Ladoga Karelia front, Finnish units retreated near the small Kollaa river, which did not in itself offer any protection, but alongside it were ridges up to 33 ft (10 m) high. The ensuing 'Battle of Kollaa' lasted until the end of the war. Further contributing to the legend of Kollaa was the sniper Simo Häyhä, dubbed 'the White Death' by the Soviets and credited with more than 500 'kills'. Kapteeni Arne Juutilainen, dubbed 'the Terror of Morocco', also became a living legend in the 'Battle of Kollaa'. To the north, the Finns retreated from Ägläjärvi to Tolvajärvi on 5 December and then repelled a Soviet offensive in the 'Battle of Tolvajärvi' on 11 December.

In the south, two Soviet divisions were united on the northern side of the Lake Ladoga shore road. As before, these divisions were trapped as the more mobile Finnish units counterattacked from the north to flank the Soviet columns. On 19 December, the exhausted Finns temporarily ceased their assaults, resuming on 6/16 January to split the Soviet divisions into smaller mottis. Contrary to Finnish expectations, the encircled Soviet divisions did not attempt to break out to the east but instead entrenched themselves as they were expecting reinforcements and supplies to arrive by air. As the Finns lacked heavy artillery and were short of men, often they did not attack the mottis directly, but instead worked to eliminate only the most dangerous threats. On several occasions, the motti tactic was not applied as a strategy but rather as a Finnish reaction to the behaviour of Soviet troops under fire. Despite the cold and their ever-increasing hunger, the Soviet troops did not surrender easily but fought bravely, often entrenching their tanks for use as pillboxes, and constructing timber dug-outs. Some specialist Finnish soldiers were summoned to attack the mottis: the most celebrated of these was Majuri Matti Aarnio, or 'Motti-Matti' as he became known.

In North Karelia, the Soviet forces were outmanoeuvred at Ilomantsi and Lieksa. The Finns made effective use of guerrilla tactics, taking special advantage of their superior skiing skills and snow-white layered clothing, and executing surprise ambushes and raids. By the end of December, the Soviets had decided to retreat and transfer resources to more critical fronts.

The Suomussalmi-Raate road engagement was a double operation that later came to be used by military academics as a classic example of what well-led troops and innovative tactics can do against a much larger adversary. Suomussalmi was a town of some 4,000 persons with long lakes, wild forests and few roads. The Finnish command believed that the Soviets would not attack there, but the Soviets in fact committed two divisions to the Kainuu area with orders to cross the wilderness, capture the city of Oulu on the north-eastern coast of the Gulf of Bothnia, and effectively cut Finland in two. There were two roads toward Suomussalmi from the frontier: the northern Juntusranta road and the southern Raate road.

The 'Battle of the Raate Road', which took place during the month-long 'Battle of Suomussalmi', resulted in one of the largest Soviet defeats of the 'Winter War'. The 44^th Division and parts of the 163^rd Division, totalling about 14,000 men, were almost completely destroyed by a Finnish ambush as they marched along the forest road. A small unit blocked the Soviet advance while Eversti Hjalmar Siilasvuo and his 9^th Division cut the Soviet retreat route, split the Soviet force into smaller mottis, and then proceeded to destroy the remnants in detail as they retreated. The Soviets suffered between 7,000 and 9,000 casualties, but the Finnish units a mere 400. The Finnish troops captured dozens of tanks, pieces of artillery, anti-tank guns, hundreds of trucks, almost 2,000 horses, thousands of rifles, and large quantities of much-needed ammunition and medical supplies. So sure of their victory had the Soviets been that a military band, complete with instruments, music and banners, was moving with the 44^th Division to perform in a victory parade.

The Finnish area of Lapland, which straddles the Arctic circle, is sparsely developed, with little daylight and persistent snow during winter. Here the Finns expected nothing more than raiding parties and reconnaissance patrols, but the Soviets instead deployed full divisions. On 11 December, the Finns rearranged their defence of Lapland and detached the Ryhmä 'Lapin' (Lapland group), under the command of Kenraalimajuri Kurt Wallenius, from the Ryhmä 'Pohjois-Suomen'.

In the southern part of Lapland, near the village of Salla, the 88^th Division and 122^nd Division, totalling some 35,000 men, advanced to the west. In the 'Battle of Salla', the Soviets advanced easily to Salla, where the road divided. Farther forward lay Kemijärvi, while the fork to Pelkosenniemi lead to the north-west. On 17 December, the Soviet northern group, comprising oner infantry regiment, one battalion and one company of tanks, was outflanked by a Finnish battalion. The 122^nd Division retreated, abandoning much of its heavy equipment and vehicles. Following this success, the Finns shuttled reinforcements to the defensive line in front of Kemijärvi, where the Soviets hammered the defensive line without success. The Finns counterattacked, and the Soviets retreated to a new defensive line on which they remained for the rest of the war.

In the far north was Petsamo, Finland’s only ice-free port on the Arctic Ocean. The Finns lacked the manpower to defend it fully, as the main front was distant at the Karelian Isthmus. In the 'Battle of Petsamo', the 104^th Division attacked the 104^th Independent Cover Company. The Finns abandoned Petsamo and concentrated on delaying actions in an area that was treeless, windy and relatively low, offering little defensible terrain. The almost constant darkness and extreme temperatures of the Lapland winter was of benefit to the Finns, who executed guerrilla attacks against Soviet supply lines and patrols. As a result, the Soviet movements were halted by the efforts of one-fifth as many Finns.

While the Soviet air forces greatly outnumbered the Finnish air force, the Soviet bombing campaign was largely ineffective, and Finnish pilots and anti-aircraft gunners inflicted significant losses on the Soviets.

The USSR enjoyed air superiority throughout the war, and the Soviet air forces supported the ground invasion with about 2,500 aircraft, of which that available in the largest numbers was the Tupolev SB-2 twin-engined light bomber, a type which had shown its effectiveness during the Spanish Civil war. The Soviet air forces were not as effective as the Soviets might have hoped, however. The material damage resulting from bomber attacks was slight, as Finland did not offer many valuable targets for strategic bombing. For example, the city of Tampere was one of the most important targets as it was an important railway junction, and also housed the State Aircraft Factory and the Tampere Linen and Iron Industry premises, which manufactured munitions and weapons, including grenade launchers. Targets were therefore often small village depots of small value. Finland had only a few modern roads, so the railway systems were the bombers' primary targets. The rail tracks were cut thousands of times but were easily repaired, and the Finns usually had trains running in a matter of hours. The damage inflicted on Finnish targets was also diminished by the Soviets' poor navigation and minimal bombing accuracy, while Finnish casualties were reduced by effective air-raid precautions. However the Soviet air forces learned from their initial mistakes, and by a time late in February 1940 had instituted more effective tactics. One such success was the strike against the Ruokolahti airfield on 29 February 1940: at 12.00 on that day 40 Polikarpov I-16 monoplane and Polikarpov I-153 biplane single-engined fighters struck the base, destroying three aircraft on the ground and another three in the air for the loss of only one I-16.

Finland’s capital city, Helsinki, was bombed on the first day of the war, when a number of buildings were destroyed and some 200 people were killed. However, the city was the target of raids only a few times thereafter. All in all, Finland lost only 5% of its total man-hour production time as a result of Soviet bombing. Nevertheless, bombings affected thousands of civilians as the Soviets launched 2,075 bombing attacks on 516 localities. Air raids killed 957 Finnish civilians, and the city of Viipuri, a major Soviet objective, was almost levelled by nearly 12,000 bombs. No attacks on civilian targets were mentioned in Soviet radio or newspaper reports: during January 1940, the Pravda newspaper continued to stress that no civilian targets in Finland had been struck, even by accident.

The largest bombing raid against Helsinki, the Finnish capital, occurred on the first day of the war, and Helsinki was bombed only a few times thereafter. All in all, Soviet bombings cost Finland 5% of its total man-hour production. Nevertheless, Soviet air attacks affected thousands of civilians, of whom 957 were killed. The Soviets recorded 2,075 bombing attacks in 516 localities. The city of Viipuri, a major Soviet objective close to the Karelian isthmus front, was almost levelled by nearly 12,000 bombs. It has been estimated that the Soviet air forces lost about 400 aircraft to inclement weather, lack of fuel and tools, and during transport to the front. The Soviet air forces flew about 44,000 sorties during the war.

Figures of Soviet losses during the conflict vary in the source material: one estimate puts the loss at between 700 and 900 aircraft, the majority of them bombers. Against this, the Finnish losses were 62 aircraft, with a further 59 damaged beyond repair. Another source states that Finnish aircraft shot down 240 Soviet aircraft, with anti-aircraft fire accounting for 314 to 444 more.

At the war’s start, Finland had only a very small air force, with a mere 114 combat aircraft fit for service. Finnish air missions were therefore very limited, and fighter aircraft were used mainly to repel Soviet bombers. Obsolescent if not actually obsolete, as well as few in number, Finnish aircraft could not offer support to the Finnish ground troops. The Finnish air force therefore adopted the same guerrilla tactics used by Finnish ground forces, dispersing to makeshift airfields often consisting only of a frozen lake. Despite losses throughout the war, the Finnish air force had grown by half by the end of the war. Most new aircraft shipments arrived during January 1940.

By this time, the Finnish air force had also revised its tactics. In air combat, the Finns used the more flexible 'finger four' formation (four aircraft split into two pairs, one flying low and the other high, with each aeroplane fighting independently of the others, yet supporting its wingman in combat), which was superior to the Soviet tactic of three fighters flying in a V formation. In combination with the tactical credo of Finnish pilots always to attack, no matter the odds, the tactic contributed to the failure of Soviet bombers to inflict substantial damage against Finnish positions and population centres.

Finnish fighter pilots often dived into Soviet formations that outnumbered them 10 or even 20 times, and Soviet bomber formations became wary of even single Finnish fighters as they knew the pilot would not let them pass without attacking. Entire squadrons could disappear on missions over Finland, and those back at their bases in Estonia could only guess at what had happened. On one occasion, the Finnish ace Jorma Kalevi Sarvanto encountered a formation of seven Ilyushin DB-3 twin-engined bombers on 6 January 1940 and shot down six of them in just four minutes.

At the start of hostilities, the Finnish air force had 146 aircraft of all types at its disposal, organised into 12 squadrons. The primary fighter aircraft were 15 Bristol Bulldog IVs, which had entered service in 1935 and 41 more modern Fokker D.XXIs. There were also 65 older Fokker aircraft of various types including the C.X and C.V biplanes, 15 Blackburn Ripon torpedo bombers and 18 licence-built Bristol Blenheim twin-engined light bombers. In 1939, an order had been placed in Italy for 25 Fiat G.50 fighters, of which two were being assembled in Sweden when the war broke out.

During the war, a number of aircraft were ordered from abroad: 30 Gloster Gladiator II biplane fighters from the UK, 12 Bristol Blenheim IV light bombers from the UK, 30 Morane-Saulnier M.S.406 fighters from France, 44 Brewster 239 fighters from the USA, 24 Gloster Gauntlet trainers from South Africa, 10 Fiat G.50 fighters from Italy, 12 Hawker Hurricane I fighters from the UK, 12 Westland Lysander tactical reconnaissance aircraft from UK, two Bristol Bulldogs from Sweden, three J6B Jaktfalken biplane trainers from Sweden, three Fokker C.V-D reconnaissance aircraft from Sweden, two Koolhoven F.K.52 reconnaissance aircraft from the Netherlands, one Douglas DC-2 transport from the Count von Rosen, Sweden, and six Caudron C.714 fighters from France, which did not enter service because of their poor performance and unsuitability for operations to and from the short landing strips in Finland.

There was also a Swedish volunteer squadron which was responsible for the air defence of northern Finland. The squadron was equipped with 12 Gladiator II biplane fighters and five Hawker Hart biplane bombers.

Owing to this reinforcement, the Finnish Air Force had a greater strength at the end of the conflict than at the beginning, but despite this fact was seldom able to field more than 100 aircraft at any one time against an expanding Soviet air commitment.

Finnish fighters shot down 240 confirmed Soviet aircraft, against the Finnish loss of 26. A Finnish forward air base often consisted only of a frozen lake, a windsock, a telephone set and some tents. Air-raid warnings were given by Finnish women organised by the Lotta Svärd. Finnish anti-aircraft gunners shot down between 314 and 444 Soviet aircraft.

There was little naval activity during the 'Winter War'. The surface of the Baltic Sea began had started to freeze by the end of December, impeding the movement of warships, and by the middle of the winter only ice-breakers and submarines could still move. The other reason for the minimal naval activity was the nature of Soviet navy forces in the area. The Baltic Fleet was a coast-defence force which did not have the training, logistical structure, or landing craft to undertake large-scale operations: the fleet possessed two battleships, one heavy cruiser, almost 20 destroyers, 50 motor torpedo boats, 52 submarines, and a miscellany of other vessels from the bases at Paldiski, Tallinn and Liepaja.

The Finnish navy was also a coast-defence force with two coast-defence ships, five submarines, four gunboats, seven motor torpedo boats, one minelayer and six minesweepers and at least five icebreakers. The two coast-defence ships, Ilmarinen and Väinämöinen, were moved to Turku harbour to bolster the air defence. Their anti-aircraft guns shot down one or two aircraft over the city, and the ships remained there for the rest of the war. On 18 January, the Finnish armed icebreaker Tarmo was severely damaged at Kotka, where she received two bomb hits and lost 39 men killed. As well as coast-defence, the Finnish navy protected the Åland islands group and Finnish merchant vessels in the Baltic Sea.

Soviet aircraft bombed Finnish vessels and harbours, and dropped mines into Finnish seaways. Even so, only five merchant ships were lost to Soviet action. World War II, which had started before the 'Winter War', proved more costly for the Finnish mercantile fleet, with 26 ships lost to hostile action in 1939 and 1940.

Finnish coastal artillery batteries defended important harbours and naval bases. Most batteries were legacies of the Imperial Russian period, with 6-in (152-mm) guns predominating. Finland attempted to modernise its old guns and installed a number of new batteries, the largest of which featured a 12-in (305-mm) battery on the island of Kuivasaari in front of Helsinki, originally intended to block the Gulf of Finland to Soviet ships with the help of batteries on the Estonian side.

The first naval battle occurred in the Gulf of Finland on 1 December, near the island of Russarö, 3.1 miles (5 km) to the south of Hanko in good weather with excellent visibility. The Finns spotted the Soviet cruiser Kirov and two destroyers, and at a range of 15 miles (24 km) the Finns opened fire with four 9.2-in (234-mm) coastal guns. Within five minutes the cruiser had been damaged by near misses and retreated. The destroyers remained undamaged, but Kirov suffered 17 dead and 30 wounded. The Soviets had known the locations of the Finnish coastal batteries, but were surprised by their range.

Coastal artillery had a greater effect on land by reinforcing defence in conjunction with army artillery. Two sets of fortress artillery made significant contributions to the early battles on the Karelian isthmus and in Ladoga Karelia. These were located at Kaarnajoki in the eastern part of the isthmus and at Mantsi on the north-eastern shore of Lake Ladoga. The fortress of Koivisto provided similar support from the south-western coast of the isthmus.

Stalin was highly displeased with the results of December in the Finnish campaign, during which the Soviet army had been humiliated. By the third week of the war, Soviet propaganda was already working to explain to the USSR’s people the failures of the Soviet military: adverse terrain and harsh climate, the false claim that the 'Mannerheim-linja' was stronger than the 'Ligne Maginot', and the equally false claim that the USA had sent 1,000 of its best pilots to Finland. Shaposhnikov, the chief-of-staff, was accordingly given full authority over operations in the Finnish theatre, and late in December he ordered the suspension of frontal assaults. Voroshilov was replaced by Komandarm 1-range Semyon K. Timoshenko as the commander of the Soviet forces in the war on 7 January. The main focus of the Soviet attack was switched to the Karelian isthmus. Timoshenko and Zhdanov reorganised and tightened control between the Soviet army’s different branches, andalso revised tactical doctrines to meet the realities of the situation.

The Soviet forces on the Karelian isthmus were divided into two major formations in the form of the 7^th Army and 13^th Army. The 7^th Army, now commanded by Meretskov, was to concentrate three-quarters of its strength against the 9.9-mile (16-km) stretch of the 'Mannerheim-linja' between Taipale and the Munasuo swamp. Tactics were to be basic: an armoured wedge for the initial breakthrough, followed by the main infantry and vehicle assault force. The Soviets would prepare by pinpointing the Finnish front-line fortifications. The 123^rd Division then rehearsed the assault on life-size mock-ups. The Soviets shipped large numbers of new tanks and pieces of artillery to the theatre. Troop strength was increased from 10 divisions to some 25 or 26 divisions together with six or seven tank brigades and several independent tank platoons as support, totalling 600,000 men. On 1 February, the Soviets launched a major offensive, firing 300,000 shells into the Finnish line in the first 24 hours of the bombardment.

Although the Karelian isthmus front was less active in January than in December, the Soviets increased the number and weight of their bombardments, wearing down the defenders and softening their fortifications. During daylight hours, the Finns took shelter inside their fortifications from the bombardments and repaired damage during the night. The situation led quickly to exhaustion among the Finns, who lost more than 3,000 men in trench warfare. The Soviets also made occasional small infantry assaults, each based on one or two companies. Because of their ammunition shortage, Finnish artillery emplacements were under orders to fire only against directly threatening ground attacks. On 1 February, the Soviets further escalated their artillery and air bombardments.

Although the Soviets refined their tactics and morale improved, their commanders were still willing to accept massive losses to reach and take their objectives. Attacks were screened by smoke, heavy artillery and supporting armour, but the infantry charged in the open and in dense formations. Unlike their practice in December, Soviet tanks advanced in smaller numbers. The Finns could not easily eliminate tanks if they were protected by infantry. After 10 days of constant artillery barrage, the Soviets achieved a breakthrough in the western part of the Karelian isthmus in the '2^nd Battle of Summa'.

By 11 February, the Soviets had approximately 460,000 men, 3,350 pieces of artillery, 3,000 tanks and 1,300 aircraft on the Karelian isthmus, and received a steady flow of new recruits after the breakthrough. Opposing them, the Finns had eight divisions, totalling about 150,000 men. One by one, the Finnish strongpoints succumbed to the Soviet attacks and the Finns were forced to retreat. On 15 February, Mannerheim authorised the general retreat of the II Armeijakunta to a fallback defence line. On the eastern side of the isthmus, the Finns continued to resist Soviet assaults, achieving a stalemate in the 'Battle of Taipale'.

Although the Finns attempted to re-open negotiations with Moscow by every means during the war, the Soviets did not respond. Early in January, the Finnish communist Hella Wuolijoki contacted the Finnish government and offered to contact Moscow through the Soviet ambassador to Sweden, Alexandra Kollontai. Wuolijoki departed for Stockholm and met Kollontai secretly at a hotel. On 29 January, Molotov put an end to the puppet 'Terijoki government' and recognised the government of Ryti and Tanner as the legal government of Finland, informing it that the USSR was willing to negotiate peace.

By the middle of February, it had become all too clear that the Finnish forces were rapidly approaching a state of exhaustion. Soviet casualties were high, the situation was a source of political embarrassment to the Soviet régime, there was a risk of French and British intervention, though this last was overestimated by Soviet intelligence in February and March, and with the spring thaw approaching there was the risk that the Soviet forces would become bogged down in the forests. Tanner, the Finnish foreign minister, arrived in Stockholm on 12 February and negotiated the peace terms with the Soviets through the Swedes. German representatives, not aware that the negotiations were already under way, suggested on 17 February that Finland should negotiate with the USSR.

Both Germany and Sweden wished to see an end to the 'Winter War'. The Germans feared losing the iron ore fields in northern Sweden and threatened to attack at once if the Swedes granted Allied forces the right of passage to Finland. Any German plans for possible bases in Finland would be thwarted should the Soviets occupy Finland: the exiled Soviet leader Leon Trotsky believed that Hitler was not interested in a German occupation of Finland, but rather its survival as a buffer between Germany and the USSR.

As the Finnish cabinet hesitated in the face of the harsh conditions demanded by the Soviet, Sweden’s King Gustav V made a public statement on 19 February in which he confirmed having declined Finnish pleas for support from Swedish troops. On 25 February, the Soviet peace terms were spelled out in detail. On 29 February, the Finnish government accepted the Soviet terms in principle and agreed that it was willing to enter into negotiations. Soviet military commanders wished to continue the war as their forces were now clearly in the ascendent, whereas the communist party pointed out that the war had been too costly and called for the signature of a peace treaty. The party believed that Finland could be subsumed later by means of a revolution. The heated discussion that ensued failed to yield any clear result and the matter went to a vote, in which the party’s opinion prevailed and the decision was taken to bring hostilities to an end.

On 5 March, the Soviet forces advanced 6.2 to 9.3 miles (10 to 15 km) past the 'Mannerheim-linja' and entered the suburbs of Viipuri. On the same day, the Soviet forces established a beach-head on the western Gulf of Viipuri. The Finns proposed an armistice on 6 March, but the Soviets, desirous of keeping the pressure on the Finnish government, declined the offer. The Finnish peace delegation travelled to Moscow via Stockholm and arrived on 7 March, and was disappointed to find that Stalin was not present during peace negotiations, probably as a result of the Soviet forces' earlier humiliation by the Finns. The Soviets had further demands, as their military position was strong and improving. On 9 March, the Finnish military situation on the Karelian isthmus was dire and the defending troops were experiencing heavy casualties. Artillery ammunition was exhausted and weapons were wearing out. Realising that the hoped-for French and British military expedition would not arrive in time, as Norway and Sweden had refused the Allies rights of passage, the Finnish government had little choice but to accept the Soviet terms. The Finnish president, Kyösti Kallio, resisted the idea of giving up any territory to the USSR, but eventually agreed to sign the Moscow Peace Treaty: when he signed the document, the tormented president said 'Let the hand wither that signs this monstrous treaty!'

The Moscow Peace Treaty was signed in Moscow on 12 March, and a cease-fire took effect on he following day at 12.00 Leningrad time (11.00 Helsinki time). In the treaty Finland ceded a portion of Karelia, the entire Karelian isthmus and territory to the north of Lake Ladoga. The area included Viipuri, Finland’s second city, much of Finland’s industrialised territory, and significant land still held by Finland’s military: these cessions amounted to 9% of Finnish territory, and included 13% of Finland’s economic assets. Some 12% of Finland’s population, in the form of between 422,000 and 450,000 Karelians, were evacuated and lost their homes. Finland also ceded part of the Salla region, the Rybachy peninsula in the Barents Sea, and four islands in the Gulf of Finland. The Hanko peninsula was leased to the USSR as a military base for 30 years. The Petsamo region, captured by the Soviet forces during the war, was returned to Finland.

Finnish concessions and territorial losses exceeded Soviet pre-war demands. Before the war, the USSR had demanded that the frontier with Finland on the Karelian isthmus be shifted westward to a point 19 miles (30 km) to the east of Viipuri along the line between Koivisto and Lipola; that existing fortifications on the Karelian isthmus be demolished; and the islands of Suursaari, Tytärsaari and Koivisto in the Gulf of Finland and the Rybachy peninsula be ceded. In exchange, the USSR proposed to cede Repola and Porajärvi from eastern Karelia, an area twice as large as the territories that were originally demanded from the Finns.

World opinion largely supported the Finnish cause, and the Soviet aggression was generally deemed unjustified. World War II had not yet directly affected France, the UK and the USA, so the 'Winter War' was practically the only active conflict in Europe at that time and thus held major world interest. Several foreign organisations sent material aid, and many countries gave credit and military matériel to Finland. Germany allowed arms to pass through its territory to Finland, but after a Swedish newspaper had revealed this fact, Hitler initiated a policy of silence toward Finland, as part of improved relations between Germany and the USSR following the signing of the Molotov-Ribbentrop Pact.

The largest foreign contingent came from neighbouring Sweden, which provided nearly 8,760 volunteers during the war. A volunteer corps was formed largely of Swedes, as well as 1,010 Danes and 727 Norwegians. This corps fought on the northern front at Salla during the last days of the war. A Swedish regiment of 12 Gladiator fighters and four Hart bombers, the 19^th Lentorykmentti was also involved. Swedish anti-aircraft batteries with Bofors 40-mm guns were responsible for air defence in northern Finland and the city of Turku. Volunteers also arrived from Hungary, Italy and Estonia, 350 US nationals of Finnish background volunteered, and 210 volunteers of other nationalities arrived in Finland before the war ended. In total, Finland received 12,000 volunteers, of whom 50 died during the war.

Finland officially refused overtures from the anti-Soviet ROV (Russian All-Military Union) for aid. Nevertheless, Mannerheim eventually agreed to establish a small Russian detachment, the RNA (Russkaya Narodnaya Armiya) of 200 men after being introduced to Boris Bazhanov, a high-ranking ROVS member, during January 1940. The project was deemed top secret, and was under the auspices of the intelligence division of the Finnish army headquarters. The ranks of the RNA were to be filled by prisoners of war, but it would be commanded by White émigrés instead of captured Soviet officers, who were deemed unreliable. Bazhanov’s Finnish assistant, Feodor Schulgin, selected Captain Vladimir Kiseleff, Lieutenant Vladimir Lugovskoy, Anatoli Budyansky, and the brothers Nikolai and Vladimir Bastamov as officers for the unit. Of the five, the Bastamov brothers were not Finnish citizens, but had Nansen passports issued by the League of Nations to stateless refugees. The prisoners of war were trained in Huittinen, although it is possible that some were also trained in Lempäälä.

The RNA was never involved in battle. Some 35 to 40 of its members were present during a battle in Ruskeala early in March 1940, where they spread flyers and broadcast propaganda to encircled Soviet troops, but did not carry weapons. The men were subsequently detained by Finnish forces, who mistook them for Soviet infiltrators. After the war’s end, Bazhanov was immediately asked to leave Finland, which he did, and it is likely that most of the RNA's members were executed after they had been returned to the USSR after the war. Bastamov was later extradited into the USSR in 1945, and was sentenced to 20 years of hard labour. He was released after Stalin’s death and returned to Finland in 1956.

France had been one of the earliest supporters of Finland during the 'Winter War', for it saw an opportunity to weaken Germany’s resource imports by means of the Finnish counter-offensive, as both Sweden and the USSR were strategic trading partners to Germany. France had another motive, preferring to have a major war in a remote part of Europe rather than on French soil, and therefore planned to re‑arm Polish exile units and transport them to the Arctic port of Petsamo. Another proposal was 'Pike', a massive French and British air attack with Turkish co-operation against the Caucasus oil fields.

The British wished to block the flow of iron ore from Swedish mines to Germany as the Swedish mines satisfied as much as two-fifths of Germany’s iron demand. The matter was raised by Admiral Sir Reginald Plunkett-Ernle-Erle-Drax, the first and principal naval aide-de-camp to King George VI, on 18 September 1939, and on the following day Winston Churchill raised the topic in the Chamberlain war cabinet. On 11 December, Churchill opined that the British should gain a foothold in Scandinavia with the objective of aiding the Finns, but without a war with the USSR. Because of the heavy German reliance on northern Sweden’s iron ore, Hitler had made it clear to the Swedish government in December that any Allied troops on Swedish soil would immediately provoke a German invasion.

On 19 December, the French prime minister, Edouard Daladier, introduced his plan to the French general staff and his war cabinet. In his plan, Daladier created link between the war in Finland and the iron ore in Sweden. There was a danger of Finland’s possible fall to Soviet hegemony. In turn, Germany could occupy both Norway and Sweden. These two powers could divide Scandinavia between them, as they had already done with Poland. The main motivation of the French and the British was to reduce German war-making capability.

The Military Co-ordination Committee met on 20 December in London, and two days later the French plan was put forward. The Anglo-French Supreme War Council elected to send notes to Norway and Sweden on 27 December, urging the Norwegians and Swedes to help Finland and offer the Allies their support. Norway and Sweden rejected the suggestion on 5 January 1940. The Allies then developed a new plan, in which they would demand that Norway and Sweden give them right of passage by citing a League of Nations resolution as justification. The expedition troops would disembark at the Norwegian port of Narvik and proceed by rail toward Finland, passing through the Swedish ore fields on the way. This demand was sent to Norway and Sweden on 6 January, but six days later was likewise rejected.

Stymied but not yet dissuaded from the possibility of action, the Allies formulated a final plan on 29 January. First, the Finns would make a formal request for assistance. Then, the Allies would ask Norway and Sweden for permission to move 'volunteer forces' across their territory. Finally, to protect these forces' supply line from German interdiction, the Allies would send units ashore at Namsos, Bergen and Trondheim. The operation would have required 100,000 British and 35,000 French soldiers with naval and air support. The supply convoys would sail on 12 March and the landings would begin on 20 March. The end of the war on 13 March terminated Franco-British plans to send troops to Finland through northern Scandinavia.

The 105-day 'Winter War' had had a profound and deeply depressing effect in Finland. Meaningful international support had been minimal and arrived late, and the German blockade had prevented most armament shipments. The 15-month period between the 'Winter War' and 'Barbarossa', of which part was the 'Continuation War', later came to be called the 'Interim Peace'. After the end of the 'Winter War', the situation of the Finnish army on the Karelian isthmus became a subject of debate in Finland. Orders had already been issued to prepare a retreat to the next line of defence in the Taipale sector. Estimates of how long the Soviets could have been delayed by retreat-and-stand operations varied from a few days to a few weeks, or indeed to a couple of months at most.

Immediately after the end of the 'Winter War', Helsinki officially announced that Finland had lost 19,576 persons killed. According to revised estimates in 2005 by Finnish historians, 25,904 people died or went missing, and 43,557 were wounded on the Finnish side during the war. Finnish and Russian researchers have estimated that between 800 and 1,100 Finns were taken prisoner, of whom between one-tenth and oner-fifth subsequently died. The USSR repatriated 847 Finns after the war. Air raids killed 957 civilians. Between 20 and 30 tanks were destroyed and 62 aircraft were lost, and Finland had to cede all ships of the Laatokan laivasto-osasto (Ladoga Naval Detachment) to the USSR.

During the 'Interim Peace', Finland attempted to improve its defensive capabilities and negotiated with Sweden on a military alliance, but negotiations ended once it became clear that both Germany and the USSR were opposed to any such alliance. On 31 July 1940, Hitler gave the order to plan an assault on the USSR and so Germany had to reassess its position regarding Finland. Until then, Germany had rejected Finnish appeals to purchase arms. However, the prospect of operations against the USSR militated for a reversal of this policy. In August, the secret sale of weapons to Finland was permitted.

Karelian evacuees established an interest group, the Finnish Karelian League, to defend Karelian rights and interests and to find a way to return ceded regions of Karelia to Finland. Finland wished to re-enter the war mainly because of the Soviet invasion of Finland during the 'Winter War', which had taken place after Finland had failed by relying on the League of Nations and on Nordic neutrality. Finland aimed primarily to reverse its territorial losses from the Moscow Peace Treaty and, depending on the success of the German invasion of the USSR, possibly to expand its borders, especially into eastern Karelia. Some right-wing groups, such as the Academic Karelia Society, supported a 'Greater Finland' ideology. The 'Continuation War' began in June 1941 and led to Finnish participation in the 'Siege of Leningrad' as well as the Finnish occupation of eastern Karelia.

The Soviet General Staff Supreme Command (Stavka) met in April 1940, reviewed the lessons of the Finnish campaign and recommended reforms. The role of front-line political commissars was reduced, and old-fashioned ranks and forms of discipline were reintroduced. Clothing, equipment and tactics for winter operations were improved. Not all of the reforms had been completed when the Germans launched 'Barbarossa' 14 months later.

Between the 'Winter War' and the period of perestroika (political reform) in the late 1980s, Soviet historiography relied solely on Molotov’s speeches on the 'Winter War'. In his radio speech of 29 November 1939, Molotov argued that the USSR had sought for two months to negotiate guarantees of security for Leningrad, but that the Finns had taken a hostile stance to 'please foreign imperialists'. Finland had undertaken military provocation, and the USSR could no longer abide by the non-aggression pacts. According to Molotov, the USSR did not wish to occupy or annex Finland, but solely to protect Leningrad.

The official Soviet figure, with reference to the command of the Leningrad Military District, was published at a session of the Supreme Soviet on 26 March 1940, with 48,475 dead and 158,863 sick and wounded. More recent Russian estimates vary: in 1990 two historians claimed 53,522 dead and 53,500 dead; in 1997, another historian claimed 126,875 dead and missing and total casualties of 391,783, with 188,671 wounded. In 1991, yet another historian claimed 63,990 dead and total casualties of 271,528, revised in 2007 to 134,000 dead, and in 2012 to 138,533. It has also been claimed that the Russian State Military Archive has a database confirming 167,976 killed or missing along with the soldiers' names, dates of birth and ranks.

Some 5,572 Soviet men was taken prisoner, and after the 'Winter War' these were returned to the USSR in accordance with the Moscow Peace Treaty. Of these, 450 were released, 4,354 were sentenced to imprisonment in labour camps ranging from 3 to 10 years and 414 were exposed to be 'active in traitorous activities while in captivity', with 334 criminal cases transferred to the Supreme Court of the Soviet Union, which handed down 232 death penalties.

The 'Winter War' was a political success for Germany: the Soviet forces and the League of Nations had each been humiliated, and the Anglo-French Supreme War Council had been revealed to be chaotic and powerless. The German policy of neutrality was unpopular in the homeland, and relations with Italy had suffered. After the Moscow Peace Treaty, Germany improved its ties with Finland, and within two weeks, Finnish-German relations were at the top of the agenda. More importantly, the very poor Soviet military performance convinced Hitler that an invasion on the USSR would be successful, the German leader declaring in June 1941 that 'we have only to kick in the door and the whole rotten structure will come crashing down'.

The 'Winter War' laid bare the disorganisation and ineffectiveness of the Soviet forces, but also those of the Allies. The Anglo-French Supreme War Council was unable to formulate a workable plan, revealing its unsuitability to make effective war. This failure led to the collapse of Daladier’s third administration in France and the nomination of Paul Reynaud as the nation’s new prime minister.