The arrows indicate the directions of the Red Army’s offensives and the defensive lines at which they were stopped. The map also indicates the most important battlegrounds. The arrows with dotted lines indicate the unreached goals of the Red Army in the different directions of attack. Edited map from the work Raunio, Ari, Sotatoimet – Suomen sotien 1939−45 kulku kartoin (Military Operations – The Course of Finnish Wars in 1939–45 with Maps), Karttakeskus, 3rd edition, 2013.

Theatres of war

The Winter War was resolved on the Karelian Isthmus, which was the main theatre of war from the very beginning. Both countries concentrated the majority of their armed forces there. The second most important front line was located in the area between Lake Ladoga and Suojärvi (Suoyarvi), where both countries deployed the second largest group of their troops. To the surprise of the Finnish General Headquarters, the Red Army attacked on the wilderness front between Suojärvi and the Arctic Ocean with a division-sized or even larger formation in several areas. The General Headquarters multiplied the number of Finnish forces deployed on the wilderness front. The leadership of the area’s troops was also changed.

Command echelons under the General Headquarters

At the start of the war, the command echelons under the General Headquarters were the 4th Army on the Karelian Isthmus, the IV Corps (IV AC) in the area between Lake Ladoga and Ilomantsi and the North Finland Group in the area between Ilomantsi and the Arctic Ocean. New command echelons were set up under the General Headquarters in early December. Detachment T, later renamed Group T, was formed under the direct command of the General Headquarters and deployed to the northern section of the IV Corps’ area of responsibility. The area between Salla and the Arctic Ocean was separated from the North Finland Group and made into an area of responsibility of the Lapland Group, which was subordinate to the General Headquarters.

The Red Army’s material resources far outnumbered those of the Finnish forces

At the start of the war, the Red Army’s ground forces had approximately 450,000 men deployed on the Finnish front. This was over one and a half times more than the entire strength of the Finnish field army, which comprised approximately 280,000 men. The material resources of the Soviet forces – such as aircraft, tanks and guns – outnumbered those of the Finns several times over. However, the Red Army’s offensive progressed with difficulty.

The Stavka took charge of the battles on the Finnish front in December

Joseph Stalin, the general secretary of the Central Committee of the Communist Party of the Soviet Union, was dissatisfied with the speed of the Red Army’s advance across the length of the Finnish front, particularly on the Karelian Isthmus. The military command of the Red Army, which had attacked Finland, was transferred from the Leningrad Military District to the Stavka, i.e. the Supreme Command of the Red Army, on 9 December.

The Stavka was chaired by the people’s commissar for defence and the commander-in-chief of the Red Army, Marshal of the Soviet Union Kliment J. Voroshilov. General Secretary of the Central Committee of the Communist Party of the Soviet Union Joseph Stalin was one of the Stavka’s members. The chief of staff of the Red Army, Army Commander 1st Rank Boris M. Shaposhnikov played an important role in the Stavka.

The offensive on Finland had until then been led by the commander of the Leningrad Military District, Army Commander 2nd Rank Kirill A. Meretskov, who was reassigned to command the 7th Army, which invaded the Isthmus.

Mannerheim was dissatisfied with the early battles on the Isthmus

Field Marshal Mannerheim was dissatisfied with the battles of the troops of the Army of the Isthmus, also called the covering forces, in the area between the national border and the main defensive line. In his opinion, the covering forces deployed in front of the main defensive line withdrew too quickly. They withdrew from their delay positions immediately upon enemy contact. The commander of the Army of the Isthmus, Jaeger Officer, Lieutenant General Hugo Österman, explained this tactic by stating that he wanted the covering forces to reach the main defensive line while they were still fit to fight.

The II Corps (II C), which was in charge of defending the western Karelian Isthmus, abandoned its delay position in Vammelsuu (Serovo) as early as 2 December. Mannerheim ordered Österman to retake Vammelsuu. On 3 December, Österman gave the II Corps the order to retake Vammelsuu. The commander of the II Corps, Jaeger Officer, Lieutenant General Harald Öhquist, told Österman that the army corps was unable to follow the order. The incident did not lead to any further measures.

Defensive battles on the Karelian Isthmus in December 1939

The Army of the Isthmus repelled an offensive by the 7th Army (7th A) of the Red Army at the Mannerheim Line in December. The hardest battles were fought in Summa and Taipale (Solovyovo). The Soviet Union’s military command halted the invasion on the Isthmus. The troops were ordered to assume defensive positions.

Increasing the Red Army’s strength in January 1940

Over the course of December, Finnish forces stopped all enemy attacks on all the other fronts as well. In January 1940, the Soviet Union doubled its assault forces to well over a million men in total. At the same time, the actual strength of the Finnish field army only increased by approximately 25,000 men, totalling 305,000 at the beginning of February. The strength of the Red Army forces on the Finnish front therefore increased to three times the strength of their Finnish counterpart. On a local level, the Red Army’s strength could be more than ten times greater than the strength of the Finnish forces.

The new Red Army troops deployed to the Finnish front were primarily concentrated on the Karelian Isthmus and on the front between Suojärvi and Lake Ladoga.

Decisive battles on the Karelian Isthmus in February 1940

In February, the Red Army launched an offensive on the Isthmus that was intended to be decisive. It led to the Mannerheim Line being breached in the Lähde sector next to Summa. The troops of the Army of the Isthmus who were deployed on the western Karelian Isthmus were ordered to retreat from the Mannerheim Line. At the end of the war, battles were being fought in the area between Vyborg Bay and the Vuoksi (Vuoksa) River on the western Karelian Isthmus, while on the eastern Karelian Isthmus battles were taking place in the Taipale area and on the new front on both sides of Vuoksi, in the Äyräpää (Baryshevo)–Vuosalmi area.

Motti battles of the IV Corps

The IV Corps (IV C) stopped an offensive by Soviet forces at the Kollaa–Kitilä (Kitelya) line. The fourth encirclement attack, launched in January, cut off the rear routes of two Soviet divisions. One of the divisions was trapped in a large-scale pocket, called motti in Finnish, in Kitilä but held out until the end of the war. The second division, which was split into several mottis, was eliminated for the most part in motti battles fought in Lemetti. The Soviet division deployed in the Lemetti area was reinforced with a tank brigade, which was also destroyed. The left flank of the area where the Finnish corps was engaged in motti battle was protected at Kollaa, which held out until the end of the war.

The doubling of the Soviet forces on the Finnish front in January 1940 led to the troops deployed in the Kollaa and Kitilä areas being multiplied. Their attacks started in March. The Finnish forces were for the most part able to maintain their positions until peace was established.

First victory achieved at Tolvajärvi (Tolvoyarvi)

In the aftermath of the loss of Suvilahti, the central village of Suojärvi, Detachment Talvela was established under the General Headquarters in the first days of December to lead battles in the Tolvajärvi and Ilomantsi areas. Its name was later changed to Group T. All forces in the area were subordinated to it. More troops were also concentrated to the group from the Field Reinforcement Brigade of the Home Troops and from the division behind the Isthmus that had served as the commander-in-chief’s reserve.

The group’s troops stopped an offensive by Red Army forces in the Ilomantsi area. In the Tolvajärvi area, the group achieved the first important victory of the Winter War by Finnish forces. After this, the troops continued their attack and captured the village of Ägläjärvi (Yaglyayarvi). The advance by the group was stopped at the Aittojoki River in January. The front line stabilised there until the end of the war.

North Finland Group

In accordance with the plans, the North Finland Group was responsible for defending the wilderness front between Lieksa and the Arctic Ocean. The group’s headquarters was located in Kajaani. The Lapland Group was separated from the North Finland Group on 11 December 1939 and made into a command echelon directly subordinate to the General Headquarters. The Lapland Group’s headquarters was located in Rovaniemi.

The most significant battles within the North Finland Group’s territory were fought in the areas of Suomussalmi–Raate and Kuhmo. The Soviet division that had captured Suomussalmi was forced out of there at the end of December, and the second division deployed to assist it was destroyed in early January on the Raate road.

A Soviet division that launched an attack in the Kuhmo area was repulsed and encircled. Some of the mottis held out until the end of the war. The Lieksa–Nurmes area and Kuusamo area were left as secondary fronts. The Soviet forces that attacked in the Lieksa and Nurmes areas retreated behind the border at the end of December.

Lapland Group

The Lapland Group led battles in the Salla and Petsamo areas. After the loss of Kuolajärvi (Kuoloyarvi), the central village of Salla, the hardest battles were fought in Joutsijärvi and

Pelkosenniemi. An attack by a Soviet rifle division was stopped in these areas. Soviet forces retreated to the Märkäjärvi–Salla line in the winter.

The Finnish General Staff had prepared for the loss of Petsamo in its plans. The Soviet Union concentrated an army comprising three divisions in the Murmansk–Petsamo area. Their main mission after occupying Petsamo was to protect the coast of the Arctic Ocean. Finnish forces fought a delaying action along the Petsamo road. By the time that peace was established, battles were being fought in Nautsi.

The Swedish volunteer unit Stridsgruppen Svenska Frivilligkåren (Battle Group SFK) assumed responsibility for the front in the area near Salla towards the end of the war. Svenska Frivilligkåren simultaneously took over the responsibility for the front from the Lapland Group. A detachment called Detachment Willamo was formed of the Finnish troops in the same area and subordinated to the Svenska Frivilligkåren, which was commanded by a Swedish general.

Ari Raunio