The Winter War was fought between Finland and the Soviet Union.
Soviet forces began the war on November 30, 1939, and it was concluded on March 12, 1940, with the Peace of Moscow.
Following the Soviet invasion of Poland in the fall of 1939, they turned their attention north to Finland. In November the Soviet Union demanded that the Finns move the border back 25km from Leningrad and grant them a 30-year lease on the Hanko Peninsula for construction of a naval base. In exchange, the Soviets offered a large tract of the Karelian wilderness. Termed as exchanging "two pounds of dirt for one pound of gold" by the Finns, the offer was flatly refused. Not to be denied, the Soviets began massing approximately 1 million men along the Finnish border.
On November 26, 1939, the Soviets faked the Finnish shelling of the Russian town of Mainila. In the aftermath of the shelling, they demanded that the Finns apologize and withdraw their forces 25km from the border. Denying responsibility, the Finns refused. Four days later, 450,000 Soviet troops crossed the border. They were met by the small Finnish army which initially numbered only 180,000. The Finns were badly outnumbered in all areas during the conflict with the Soviets also possessing superiority in armor (6,541 to 30) and aircraft (3,800 to 130).
Course of the War:
Led by Marshal Carl Gustav Mannerheim, Finnish forces manned the Mannerheim Line across the Karelian Isthmus. Anchored on the Gulf of Finland and Lake Lagoda, this fortified line saw some of the heaviest fighting of the conflict. To the north Finnish troops moved to intercept the invaders. Soviet forces were overseen by the skilled Marshal Kirill Meretskov but suffered heavily at lower command levels from Josef Stalin's purges of the Red Army in 1937. Advancing, the Soviets had not anticipated meeting heavy resistance and lacked winter supplies and equipment.
Generally attacking in regimental strength, the Soviets in their dark uniforms presented easy targets for Finnish machine gunners and snipers. One Finn, Corporal Simo Häyhä, recorded over 500 kills as a sniper. Utilizing local knowledge, white camouflage, and skis, Finnish troops were able to inflict staggering casualties on the Soviets. Their preferred method was the use of "motti" tactics which called for fast-moving light infantry to swiftly encircle and destroy isolated enemy units. As the Finns lacked armor, they developed specialized infantry tactics for dealing with Soviet tanks.
Utilizing four-man teams, the Finns would jam the tracks of enemy tanks with a log to stop it then use Molotov Cocktails to detonate its fuel tank. Over 2,000 Soviet tanks were destroyed using this method. After effectively halting the Soviets during December, the Finns won a stunning victory on the Raate Road near Suomussalmi in early January 1940. Isolating the Soviet 44th Infantry Division (25,000 men), the Finnish 9th Division, under Colonel Hjalmar Siilasvuo, was able to break the enemy column into small pockets that were then destroyed. Over 17,500 were killed in exchange for around 250 Finns.
The Tide Turns:
Angered by Meretskov's failure to break the Mannerheim Line or achieve success elsewhere, Stalin replaced him with Marshall Semyon Timoshenko on January 7. Building up Soviet forces, Timonshenko launched a massive offensive on February 1, attacking the Mannerheim Line and around Hatjalahti and Muolaa Lake. For five days the Finns beat back the Soviets inflicting horrifying casualties. On the sixth, Timonshenko began assaults in West Karelia which met a similar fate. On February 11, the Soviets finally achieved success when they penetrated the Mannerheim Line in several places.
With his army's ammunition supply nearly exhausted, Mannerheim withdrew his men to new defensive positions on the 14th. Some hope did arrive when the Allies, then fighting World War II, offered to send 135,000 men to aid the Finns. The catch in the Allies' offer was that they requested that their men be allowed to cross Norway and Sweden to reach Finland. This would have allowed them to occupy the Swedish iron ore fields that were supplying Nazi Germany. Upon hearing of the plan Adolf Hitler stated that should Allied troops enter Sweden, Germany would invade.
The situation continued to worsen through February with the Finns falling back towards Viipuri on the 26th. On March 2, the Allies officially requested transit rights from Norway and Sweden. Under threat from Germany, both countries denied the request. Also, Sweden continued to refuse to intervene directly in the conflict. With all hope of substantial outside assistance lost and the Soviets on the outskirts of Viipuri, Finland dispatched a party to Moscow on March 6 to begin peace negotiations.
Finland had been under pressure from both Sweden and Germany for nearly a month to seek and end to the conflict, as neither nation wished to see a Soviet takeover. After several days of talks, a treaty was completed on March 12 which ended the fighting. By the terms of the Peace of Moscow, Finland ceded all of Finnish Karelia, part of Salla, the Kalastajansaarento Peninsula, four small islands in the Baltic, and was forced to grant a lease of the Hanko Peninsula. Included in the ceded areas was Finland's second-largest city (Viipuri), most of its industrialized territory, and 12% of its population. Those living in the affected areas were permitted to move to Finland or remain and become Soviet citizens.
The Winter War proved a costly victory for the Soviets. In the fighting, they lost approximately 126,875 dead or missing, 264,908 wounded, and 5,600 captured. In addition, they lost around 2,268 tanks and armored cars. Casualties for the Finns numbered around 26,662 dead and 39,886 wounded. The Soviet's poor performance in the Winter War led Hitler to believe that Stalin's military could be quickly defeated if attacked. He attempted to put this to the test when German forces launched Operation Barbarossa in 1941. The Finns renewed their conflict with the Soviets in June 1941, with their forces operating in conjunction with, but not allied to, the Germans.