In Europe in 1939, German fascists completely occupied Poland. In August, the Soviet Union and Germany signed a "non-aggression pact" that recognized each other's spheres of influence. As a result, Poland was divided between the Soviet Union and Germany, and the three Baltic states (Lithuania, Latvia, and Estonia) also belonged to the Soviet Union. At this time, Stalin decided to take advantage of this opportune opportunity to solve the Finnish problem. Because Finland controlled the Karelian Isthmus and its nearby islands, it jammed the Soviet Union's access to the Baltic Sea, squeezing the Soviet Strategic Space in the Baltic Sea, a situation that the increasingly powerful Soviet Union could not tolerate in the 1930s. Thus, on November 30, 1939, the Soviet-Finnish War broke out, and the horns of the Soviet Red Army sounded everywhere on the snowy plains bordering Finland and the Soviet Union, from the Baltic Sea to the Arctic Ocean, from south to north, along the Leningrad-Murmansk railway line. Amid the sound of a tsunami of "ulla", endless infantry, artillery and tanks drove from a number of different assembly points into the Finnish hinterland. The Red Army was strong, with a total strength of 540,000 troops, including the 7th, 8th, 9th, and 14th Armies, a total of 25 divisions, and the Soviet Supreme Staff set a campaign time of 12 to 15 days to fully occupy Finland. But the Soviet Union was not Germany, and Finland was not Poland. In response to the Soviet Union, Finland built the iron-walled Mannerheim Line in the Karelian Isthmus. Marshal Managhan was originally a Tsarist general, a Swedish-Finn, who returned to Finland after the October Revolution. After the Soviet-Finnish War, the 73-year-old Mannahan was appointed commander-in-chief of the Finnish army, commanding nine Finnish infantry divisions against the Soviets. He took advantage of the Finnish climate and terrain to form guerrilla detachments and sniper detachments to inflict heavy casualties on the Soviet army, the most famous Finnish ace sniper killed an entire Soviet reinforcement battalion, and another major invention of the Finnish army was the "Molotov cocktail", that is, the Molotov cocktail, a large glass bottle filled with some gasoline, kerosene, and after lighting it with a cloth strip, it could easily destroy a tank. The Soviet-Finnish War lasted for 5 months, and according to the memoirs of Khrushchev, a witness to the war, the Soviet army wounded nearly one million people, 200,000 people were killed, and Finland's losses were also huge. The performance of the Soviet army allowed Hitler to see the opportunity to easily destroy the Soviet Union, and formulated the "Barbarossa" plan for Nazi Germany to raid the Soviet Union, and then the vengeful Finland joined the German camp to attack the Soviet Union, but after World War II, it was again divided by the Soviet Union. Painfully, Finland, which had been shattered from the Nordic fairy tale, chose the position of permanent neutrality and did not join any military alliance.