By March, they were close to exhaustion, but the scale of Soviet losses combined with fears of international intervention and the mud of the coming Spring thaw, drove Moscow to negotiate.
Finland paid a high price for its survival, losing nine per cent of its national territory, including the Karelian Isthmus, as well as 70,000 casualties. It would also face a renewed Soviet invasion in 1941, which it would survive only with Nazi support.
The country learnt a vital lesson, however.
Civilian population ready for crisis
Outside of Nato and with the Soviet threat ever-present, Finland would make itself so difficult to digest as to not be worth invading at all.
Almost a third of the Finnish population is a reservist, giving it nearly a million trained people to draw on. Its air force can scatter and operate from remote roads, while plans are in place to blow up bridges and mine shipping lanes.
Civilian society is also prepared to survive a crisis, with everything from banks to the media having a plan and thousands of bomb shelters scattered among civilian buildings.