The Winter War was a conflict fought between the Soviet Union and Finland from November 30, 1939, to March 13, 1940. The war began when the Soviet Union invaded Finland, seeking to gain territory and secure its northwestern borders. Despite being heavily outnumbered and outgunned, Finnish forces utilized their knowledge of the harsh winter terrain and guerrilla tactics to resist the invasion effectively. The war ended with the Moscow Peace Treaty, which resulted in Finland ceding about 11% of its territory to the Soviet Union. Although Finland lost land, the conflict boosted national unity and military reputation, demonstrating the resilience of the Finnish people against a larger adversary.