Errrr.... really?
You might want to look up The Winter War et seq.
https://www.britannica.com/event/Russo-Finnish-War
In February 1940, however, the Soviets used massive artillery bombardments to breach the Mannerheim Line (the Finns’ southern defensive barrier stretching across the Karelian Isthmus), after which they streamed northward across the isthmus to the Finnish city of Viipuri (Vyborg). Unable to secure help from Britain and France, the exhausted Finns made peace (the Treaty of Moscow) on Soviet terms on March 12, 1940, agreeing to the cession of western Karelia and to the construction of a Soviet naval base on the Hanko Peninsula.