World War II

A nonaggression pact with the Soviet Union was signed in 1932 and renewed in 1934. In October, 1939, the Soviet Union demanded that Finland give up certain strategic areas near Leningrad and Kronshtadt, and grant a 30-year lease on the Hangö Peninsula at the entrance to the Gulf of Finland. In return, the Soviet Union offered territory north of Lake Ladoga. Finland rejected only the demand for the Hangö lease, on the grounds that it would violate Finnish neutrality. After three weeks of negotiations, the Soviets renounced the nonaggression pact and attacked Finland.

In the war that followed, called the Russo-Finnish War, or Winter War, the Finns resisted bravely, winning widespread sympathy, but not much practical aid. The Finns held back the Soviets in the fall of 1939, but were defeated the following spring. In March, 1940, Finland signed a peace treaty ceding to the Soviet Union the Karelian Isthmus, several islands, territory around Lake Ladoga, and the western part of the Rybachiy Peninsula. Finland also gave the Soviets a 30-year lease on Hangö Peninsula. (

In 1940 Finland granted German troops permission to cross the country to invade Norway. When Germany attacked the Soviet Union in 1941, Finnish troops also attacked. Soon after, Finland signed a pact with the Axis powers. Great Britain declared war on Finland, and the United States interned Finnish ships in American ports.

During 1941, the Finns captured southern Karelia and regained most of the territory lost in 1940. As Germany's position weakened, however, many Finns began wishing for peace. In February, 1944, Finland was warned by the United States not to continue the war. Peace discussions began, but the Finns twice refused the Soviet Union's terms. The Soviets opened a full-scale offensive, broke through the Mannerheim Line, and captured the port of Viipuri (now Vyborg). Nevertheless, in June, 1944, Finland signed an agreement with Germany pledging to continue the war. The United States severed diplomatic relations with Finland but did not declare war.

By this time few people in Finland wished the war to continue. In August the government was forced to resign, Mannerheim became president, and the Finnish-German agreement of June was denounced. A peace treaty with Great Britain and the Soviet Union reduced Finland to its 1940 boundaries and gave the Petsamo area back to the Soviet Union. The Soviets gave up the Hangö lease in exchange for a 50-year lease on the Porkkala headland, near Helsinki.