Finland's nearly 700-year association with the Kingdom of Sweden began in 1154 with the introduction of Christianity by Sweden's King Eric. During the ensuing centuries, Finland played an important role in the political life of the Swedish-Finnish realm, and Finnish soldiers often predominated in Swedish armies. Finns also formed a significant proportion of the first "Swedish" settlers in 17th-century America.

Following Finland's incorporation into Sweden in the 12th century, Swedish became the dominant language, although Finnish recovered its predominance after a 19th-century resurgence of Finnish nationalism. Publication in 1835 of the Finnish national epic, The Kalevala--a collection of traditional myths and legends--first stirred the nationalism that later led to Finland's independence from Russia.

In 1809, Finland was conquered by the armies of Czar Alexander I and thereafter remained an autonomous grand duchy connected with the Russian Empire until the end of 1917. On December 6, 1917, shortly after the Bolshevik Revolution in Russia, Finland declared its independence. In 1918, the country experienced a brief but bitter civil war that colored domestic politics for many years. During World War II, Finland fought the Soviet Union twice--in the Winter War of 1939-40 and again in the Continuation War of 1941-44. This was followed by the Lapland War of 1944-45, when Finland fought against the Germans as they withdrew their forces from northern Finland.

Treaties signed in 1947 and 1948 with the Soviet Union included obligations and restraints on Finland vis-a-vis the U.S.S.R. as well as territorial concessions by Finland; both have been abrogated by Finland since the 1991 dissolution of the Soviet Union (see Foreign Relations).