7. The Soviet-Finnish Winter War (1939-1940)
The Soviet Union initiated the Winter War by invading Finland on November 30, 1939, without a formal declaration of war. (britannica.com) Despite being heavily outnumbered, Finnish forces mounted a determined defense, utilizing guerrilla tactics and exploiting the harsh winter conditions. (history.com) The conflict resulted in significant casualties on both sides and concluded with the Moscow Peace Treaty on March 12, 1940, which required Finland to cede substantial territory to the Soviet Union. (britannica.com)
