Soviet-Finnish War of 1939–40

The Soviet-Finnish War of 1939–40, also known as the Winter War, broke out as a result of the policies of the reactionary Finnish government, which had made Finland a potential springboard for an attack on the USSR by aggressive powers.

Finland’s hostile attitude toward the USSR posed a serious threat to the northwest Soviet border and placed Leningrad in danger. In preparing for war, Finland devoted particular attention to the construction of fortifications in its border regions, especially on the Karelian Isthmus, where the frontier was only 32 km from Leningrad. Finland received financial aid from Great Britain, Sweden, Germany, and the USA. These funds made possible the construction of the Mannerheim Line. Pursuing a policy of peace and concerned for the security of the USSR at a time of increasing fascist German aggression, the Soviet government made several attempts in 1938 and 1939 to improve relations with Finland.

In April 1938 the Soviet government proposed negotiations toward a mutual assistance pact, but the Finnish government rejected the proposal. In October 1939, after the beginning of World War II, the USSR again proposed the conclusion of a mutual assistance pact, but Finland’s response was negative. Influenced by the USA, Great Britain, France, and Hitlerite agents, the Finnish government adopted a hostile attitude toward the USSR. On October 13 and 14, Finland announced the mobilization of its forces. Since the Finnish government was unwilling to conclude a treaty of mutual assistance, the USSR on October 14 requested that it be permitted to lease the Hanko Peninsula. In addition, an exchange of territory was requested: if Finland agreed to cede a number of islands in the Gulf of Finland and certain areas on the Karelian Isthmus, on the Rybachii Peninsula, and on the Srednii Peninsula, compensation would be provided in the form of an area twice as large in Soviet Karelia. Although these proposals did not infringe on Finnish sovereignty, they were rejected by the Finnish side.

After the negotiations broke down, the Finnish government declined to consider any new Soviet proposals and brought its military forces into a state of readiness. By late November 1939 the Finnish armed forces, numbering 600,000 men, consisted of nine infantry divisions, five infantry brigades, five separate infantry regiments, 22 separate infantry battalions, one cavalry brigade, approximately 900 artillery pieces, and 60 tanks; naval and air support was provided by 29 warships and approximately 270 combat aircraft. The main ground forces were concentrated on the Karelian Isthmus. They were under the command of General H. V. Óstermann and consisted of six infantry divisions, four infantry brigades, one cavalry brigade, and several separate battalions. Special groups and strategic formations were created on the Murmansk, Kandalaksha, Ukhta, Reboly, and Petrozavodsk axes. The commander in chief was Marshal C. von Mannerheim.

An anti-Soviet campaign developed in Finland. Counting on assistance from Western powers, the Finnish militarists on November 26 entered on the path of military provocations at the border. The Soviet government proposed that Finnish troops on the Karelian Isthmus be pulled back a distance of 20–25 km. Finland, however, did not accept this proposal and further exacerbated the situation. On November 28 the Soviet government was compelled to denounce the Soviet-Finnish nonaggression pact of 1932.

The Finnish government paid no heed to the warnings of the USSR. On November 29, Finnish troops again staged provocative actions at the border. In response, the forces of the Leningrad Military District, supported by the Northern and Baltic fleets, launched an offensive on the morning of November 30 along a front extending from the Barents Sea to the Gulf of Finland. The Soviet Union had no choice but to take this step. Even after the beginning of hostilities, the Soviet government proposed that a most comprehensive treaty of friendship and mutual assistance be concluded, but this initiative was rejected by the Finnish government, which declared war on the USSR on November 30.

Under the command of Army Commander Second Class K. A. Meretskov and Military Council member A. A. Zhdanov, the forces of the Leningrad Military District were deployed along a front 1,500 km in length: the Fourteenth Army (two rifle divisions) on the Murmansk axis; the Ninth Army (three rifle divisions) on the Kandalaksha, Ukhta, and Reboly axes; the Eighth Army (four rifle divisions) on the Petrozavodsk axis; and the Seventh Army (nine rifle divisions, one tank corps, three separate tank brigades, and 13 artillery regiments) on the Karelian Isthmus. Combat operations were supported by nine air regiments and the Baltic Fleet. The plan of operations was to pin down the Finnish forces in northern and central Finland while the Seventh Army delivered the main blow on the Karelian Isthmus in the general direction of Viipuri (Vyborg); the Seventh Army was to reach the line extending from the railroad station Hiitola to Viipuri by the ninth or tenth day of the offensive.

The fighting took place on a terrain with numerous lakes and forests and under severe winter conditions. The temperature ranged from - 40° to - 45°C, and the deep snow prevented crosscountry movement. The most difficult battles took place on the Karelian Isthmus. Under Army Commander Second Class V. F. Iakovlev and, from December 9, Army Commander Second Class Meretskov, the Seventh Army advanced slowly, with air and naval support, against stubborn enemy resistance. After heavy fighting, the Soviet forces managed by December 12 to break through a difficult strategic obstacle belt 25 km to 65 km deep and to reach the forward edge of the main defense zone of the Mannerheim Line. On December 29 the Soviet command decided to halt the advance on the Karelian Isthmus and to make preparations for breaching the Mannerheim Line.

The Baltic Fleet, under Flag Officer Second Class V. F. Tributs, took a number of islands in the Gulf of Finland and blockaded the coasts of the Gulf of Bothnia and the Gulf of Finland. North of Lake Ladoga, the offensive involved the following forces: the Fourteenth Army, under Division Commander V. A. Frolov, and the Northern Fleet, under Flag Officer Second Class V. P. Drozd, in the Polar region on the Petsamo axis; the Ninth Army, under Corps Commander M. P. Dukhanov and, from mid-December, Corps Commander V. I. Chuikov, on the Kandalaksha, Ukhta, and Reboly axes; and the Eighth Army, under Division Commander I. N. Khabarov and, from January, Army Commander Second Class G. M. Shtern, on the Petrozavodsk axis. These forces broke through the enemy’s border fortifications and by mid-December had advanced a considerable distance despite enemy resistance.

In late December the Seventh Army was divided into the Seventh Army and the Thirteenth Army, which was commanded first by Corps Commander V. D. GrendaF and then, from March 2, by Corps Commander F. A. Parusinov. The two armies were reinforced by troops from other military districts. A new Fifteenth Army, under Army Commander Second Class M. P. Kovalev, was formed from the Eighth Army. On January 7 the Northwestern Front was established on the Karelian Isthmus. Commanded by Army Commander First Class S. K. Timoshenko and Military Council member Zhdanov, the Northwestern Front included 24 rifle divisions, a tank corps, five separate tank brigades, 21 artillery regiments, and 23 air regiments. The objective of the Northwestern Front was to break through the Mannerheim Line, defeat the principal enemy forces on the Karelian Isthmus, and, in 13 to 18 days, reach the line running from Käkisalmi through the railroad station Antrea to Viipuri. The main effort was in the general direction of Antrea. A reserve group of the Soviet High Command was established for the purpose of carrying out, across the Gulf of Finland, a wide deep envelopment of the enemy forces around Viipuri. This reserve group consisted of one cavalry corps, three rifle divisions, and one tank brigade.

The forces of the Northwestern Front began the offensive on February 11, after two or three hours of preparatory artillery fire. After heavy fighting, the Seventh Army broke through the main zone of the Mannerheim Line and approached the second zone. The Thirteenth Army broke through the forward position of the Mannerheim Line and approached the main zone. Fearing that the Soviet forces might gain the rear of the Finnish main grouping, the Finnish command on the night of February 17 began withdrawing its troops to the main (in the zone of advance of the Thirteenth Army) and second (in the zone of advance of the Seventh Army) zones of the Mannerheim Line. On February 21 the Seventh Army reached the second zone of the Mannerheim Line, and the Thirteenth Army reached the main zone. The Soviet forces, however, were not immediately able to break through the enemy positions. North of Lake Ladoga, the Ninth, Eighth, and, beginning in February, Fifteenth armies also advanced. After a short pause, the Soviet forces resumed their offensive on February 28. They broke the enemy’s resistance and forced a retreat along the entire front. Continuing their offensive, they outflanked, from the northeast, the Finnish units around Viipuri and captured most of Viipuri. Soviet forces crossed Viipuri Bay, went around the Viipuri fortified area from the northwest, and cut the road to Helsinki. The breaking of the Mannerheim Line and the defeat of the Finnish main grouping placed the enemy in a difficult situation. The enemy was not saved by the assistance of the Western powers: during the war, Finland received, for example, 350 planes, 1,500 artillery pieces, more than 6,000 machine guns, approximately 100,000 rifles, and 2.5 million shells.

The Soviet-Finnish peace treaty of 1940 was signed in Moscow on March 12. Military operations ceased on March 13. The treaty moved the border on the Karelian Isthmus to a distance of 150 km from Leningrad; the border was also moved northwest of Lake Ladoga and in the Salla (Kuolajárvi) region. Portions of the Srednii and Rybachii peninsulas were ceded to the USSR, and the USSR was granted the right to lease the Hanko Peninsula for 30 years. The USSR obligated itself to withdraw its forces from the region of Petsamo (now Pechenga).

During the war the Red Army gained experience in breaking through heavily fortified areas under severe winter and snow conditions. This experience was put to use in developing tactics and operational art and in the combat training of troops.