The Russo-Finnish War, also known as the Winter War, erupted on 30 November 1939 when 30 infantry divisions and six tank brigades of the Soviet Red Army, roughly half-a-million men and 2,000 vehicles, invaded neighbouring Finland.
The Finnish Army numbered only about 300,000, while the Soviet Union mustered more than 1.5 million troops under arms; facing overwhelming odds, the Finns possessed few tanks and an antiquated air force primarily composed of biplanes. However, the defenders were well led and exhibited tremendous resourcefulness and superior tactics, thwarting Soviet designs for a quick victory and gaining the admiration of the world. The Finns inflicted serious defeats on the Red Army, which suffered staggering casualties, and held out for more than 100 days before the conflict ended in Soviet victory on 13 March 1940.
Mutual mistrust
Despite the conclusion of the Nazi-Soviet non-aggression pact of August 1939 and the cooperation of the Soviet Red Army and German Wehrmacht in the invasion and partition of Poland in September, Joseph Stalin remained wary of Hitler and the Nazis. Stalin feared a German invasion of the Soviet Union and believed that the armies of the Third Reich might use Scandinavia, particularly the lowlands of Finland, as an avenue of attack on Leningrad, a major city in the north of Russia.
To counter this perceived threat, Stalin made political overtures to the leaders of the Baltic States of Estonia, Latvia and Lithuania, persuading them to make concessions that would allow a better Soviet defensive posture against any German aggression. When the Soviets approached the Finns, however, the latter proved much less malleable than the Baltic leaders. The Finns refused to grant the Soviets occupation of several islands in the Gulf of Finland, a long-term lease for a naval base at Hanko, and other concessions that would extend Soviet defensive capabilities on the Karelian Isthmus, separating the Gulf of Finland and expansive Lake Ladoga, even when offered Russian territory in exchange. The Finns believed that an early indication that they
