Who fought the "Winter War"?

The Winter War was a military conflict between the Soviet Union and Finland in 1939–1940. It began with the Soviet invasion of Finland on 30 November 1939 (three months after the outbreak of World War II), and ended with the Moscow Peace Treaty on 13 March 1940. The Soviet Union ostensibly sought to claim parts of Finnish territory, demanding that Finland cede substantial border territories, claiming security reasons, primarily the protection of Leningrad, which was only 32 km (20 mi) from the Finnish border.

The Soviets possessed more than three times as many soldiers as the Finns, thirty times as many aircraft, and a hundred times as many tanks. The Red Army, however, had been crippled by Stalin's Great Purge of 1937. With more than 30,000 of its officers executed or imprisoned, including most of those of the highest ranks, the Red Army in 1939 had many inexperienced officers. Because of this and high morale in the Finnish forces, Finland repelled Soviet attacks for several months, much longer than the Soviets expected.

However, after reorganization and adoption of different tactics, the renewed Soviet offensive overcame Finnish defenses at the borders. Finland then agreed to cede more territory than originally demanded by the Soviet Union in 1939; the Soviets, having conquered the areas they demanded from Finland but at a cost of heavier losses in troops than anticipated, accepted this offer.