Winter War in the context of "Neutral state"

World War II or the Second World War (1 September 1939 – 2 September 1945) was a global conflict between two coalitions: the Allies and the Axis powers. Nearly all of the world's countries participated, with many nations mobilising all resources in pursuit of total war. Tanks and aircraft played major roles, enabling the strategic bombing of cities and delivery of the first and only nuclear weapons ever used in war. World War II is the deadliest conflict in history, causing the death of 70 to 85 million people, more than half of whom were civilians. Millions died in genocides, including the Holocaust, and by massacres, starvation, and disease. After the Allied victory, Germany, Austria, Japan, and Korea were occupied, and German and Japanese leaders were put on trial for war crimes.

The causes of World War II included unresolved tensions in the aftermath of World War I, the rise of fascism in Europe and militarism in Japan. Key events preceding the war included Japan's invasion of Manchuria in 1931, the Spanish Civil War, the outbreak of the Second Sino-Japanese War in 1937, and Germany's annexations of Austria and the Sudetenland. World War II is generally considered to have begun on 1 September 1939, when Nazi Germany, under Adolf Hitler, invaded Poland, after which the United Kingdom and France declared war on Germany. Poland was divided between Germany and the Soviet Union under the Molotov–Ribbentrop Pact. In 1940, the Soviet Union annexed the Baltic states and parts of Finland and Romania. After the fall of France in June 1940, the war continued mainly between Germany, now assisted by Fascist Italy, and the British Empire, with fighting in the Balkans, Mediterranean, and Middle East, the aerial Battle of Britain and the Blitz, and the naval Battle of the Atlantic. Through campaigns and treaties, Germany gained control of much of continental Europe and formed the Axis alliance with Italy, Japan, and other countries. In June 1941, Germany invaded the Soviet Union, opening the Eastern Front and initially making large territorial gains.

The Moscow Peace Treaty was signed by Finland and the Soviet Union on 12 March 1940, and the ratifications were exchanged on 21 March. It marked the end of the 105-day Winter War, upon which Finland ceded border areas to the Soviet Union. The treaty was signed by Vyacheslav Molotov, Andrei Zhdanov and Aleksandr Vasilevsky for the Soviet Union, and Risto Ryti, Juho Kusti Paasikivi, Rudolf Walden and Väinö Voionmaa for Finland. The terms of the treaty were not reversed after the dissolution of the Soviet Union. The Karelian question refers to the debate within Finland over the possible reacquisition of this ceded territory.

The Finnish Democratic Republic (Finnish: Suomen kansanvaltainen tasavalta or Suomen kansantasavalta, Swedish: Demokratiska Republiken Finland, Russian: Финляндская Демократическая Республика), also known as the Terijoki Government (Finnish: Terijoen hallitus), was a short-lived puppet government of the Soviet Union in occupied Finnish territory from December 1939 to March 1940.

The Finnish Democratic Republic was established by Joseph Stalin upon the outbreak of the Winter War and headed by Otto Wille Kuusinen to govern Finland after Soviet conquest. The Finnish Democratic Republic was only recognised by the Soviet Union and nominally operated in Soviet-occupied areas of Finnish Karelia from the de facto capital of Terijoki. The Finnish Democratic Republic was portrayed by the Soviet Union as the official socialist government of Finland capable of restoring peace, but lost favor as the Soviets sought rapprochement with the Finnish Government. The Finnish Democratic Republic was dissolved and merged into the Karelo-Finnish SSR upon the signing of the Moscow Peace Treaty.

The Battle of Taipale was a series of battles fought during the Winter War between Finland and Soviet Union from 6 to 27 December 1939. The battles were part of a Soviet campaign to penetrate the Finnish Mannerheim Line in the Karelian Isthmus region to open a route into southern Finland. Despite their numerical superiority, the Soviet forces were unable to break through the Finnish defences.

The Karelian Isthmus (Russian: Карельский перешеек, romanized: Karelsky peresheyek; Finnish: Karjalankannas; Swedish: Karelska näset) is the approximately 45–110-kilometre-wide (30–70 mi) stretch of land situated between the Gulf of Finland and Lake Ladoga in northwestern Russia, to the north of the River Neva. Its northwestern boundary is a line from the Bay of Vyborg to the westernmost point of Lake Ladoga, Pekonlahti. If the Karelian Isthmus is defined as the entire territory of present-day Saint Petersburg and Leningrad Oblast to the north of the Neva and also a tiny part of the Republic of Karelia, the area of the isthmus is about 15,000 km (5,800 sq mi).

The smaller part of the isthmus to the southeast of the old Russia-Finland border is considered historically as Northern Ingria, rather than part of the Karelian Isthmus itself. The rest of the isthmus was historically a part of Finnish Karelia. This was conquered by the Russian Empire during the Great Northern War in 1712 and included within the autonomous Grand Duchy of Finland (1809–1917) of the Russian Empire. When Finland became independent in 1917, the isthmus (except for the territory roughly corresponding to present-day Vsevolozhsky District and some districts of Saint Petersburg) remained Finnish. Finnish Karelia was partly ceded to the Soviet Union by Finland following the Winter War (1939–1940) and Continuation War (1941–1944). In 1940–1941, during the Interim Peace, most of the ceded territories in the isthmus were included within the Karelo-Finnish SSR. However, since World War II the entire isthmus has been divided between the city of Saint Petersburg (mostly Kurortny District), as well as Priozersky District, Vsevolozhsky District and Vyborgsky District of Leningrad Oblast.