The pagan Liths, or Lithuanians, may have settled along the Nemen as early as 1500 B.C. In the 13th cent. the Livonian Brothers of the Sword and the Teutonic Knights conquered the region now comprising Estonia, Latvia, and parts of Lithuania. To protect themselves against the Knights, who pressed them from the north and the south, the Lithuanians formed (13th cent.) a strong unified state.
The grand dukes Gedimin (1316–41) and Olgerd (1345–77) expanded their territories at the expense of the neighboring Russian principalities, which were weakened by the Mongol invasion. Lithuania became one of the largest states of medieval Europe, including all of what is now Belarus, a large part of Ukraine, and sections of European Russia; at its furthest extent it touched the Black Sea. Olgerd's son, Jagiello, became king of Poland in 1386 as Ladislaus II by his marriage with Jadwiga, daughter of Louis I of Poland and Hungary. He accepted and introduced Christianity.
The union between Lithuania and Poland had at first the character of an alliance between independent nations. Witowt, a cousin of Ladislaus II, ruled Lithuania independently (1392–1430) and brought it to the height of its power and expansion. In 1410 the Polish-Lithuanian forces severely defeated the Teutonic Knights at Tannenberg and Novgorod.
After Witowt's death, decline set in. The Belarusians, who had retained their Greek Orthodox faith, inclined toward the rising grand duchy of Moscow. In 1569, hard pressed by the Russians under Ivan IV, Lithuania was joined with Poland by the Union of Lublin to form a commonwealth. The Lithuanian aristocracy and burghers became thoroughly Polonized. By the three successive partitions of Poland (1772, 1793, 1795) Lithuania disappeared as a national unit and passed to Russia.
A Lithuanian linguistic and cultural revival began in the 19th cent., inspired largely by the Roman Catholic clergy and accompanied by frequent anti-Russian uprisings. World War I and the consequent collapse of Russia and Germany made Lithuanian independence possible. Proclaimed (Feb., 1918) an independent kingdom under German protection, Lithuania became (Nov., 1918) an independent republic.
It resisted attacks by Bolshevik troops and by volunteer bands of German adventurers, but in 1920 Vilnius was seized by Poland. Lithuania remained technically at war with Poland until 1927. In 1923, Lithuania seized the Memel Territory. The virtual dictatorship (1926–29) of Augustine Voldemaras was succeeded (1929–39) by that of Antanas Smetona, and an authoritarian constitution on corporative (fascist) lines became effective in 1938.
Vilnius passed to Lithuania after the Soviet-German partition of Poland in 1939, but a German ultimatum forced the restitution of Memel. In 1940 the USSR, which had obtained military bases in Lithuania, occupied the country. After a Soviet-sponsored "election," Lithuania became a constituent republic of the USSR. When Germany invaded Lithuania in June, 1941, there was an insurrection against the Soviets and a provisional government was established, but Germany refused to recognize Lithuanian independence, and the government was disbanded. During the German occupation (1941–44) of Lithuania in World War II, the considerable Jewish minority was largely exterminated. In 1944 the Communist government returned. An anti-Communist guerrilla movement was active in the late 1940s and early 1950s; meanwhile, there were massive deportations of intellectuals and farmers to European Russia, Central Asia, and Siberia. After the death of Joseph Stalin in 1953, repression eased somewhat, and ethnic Lithuanians became prominent in the Communist elite.
In Mar., 1990, the Lithuanian parliament declared independence from the Soviet Union. Sajudis, a non-Communist coalition, won control of the Lithuanian parliament, and Vytautas Landsbergis became Lithuania's president. The Soviet Union responded with an oil embargo and troop actions in which civilians were killed. A referendum on independence passed in Feb., 1991, and Lithuania's independence was recognized by the Soviet Union on Sept. 6, 1991. In 1992, the Democratic Labor (formerly the Communist) party defeated Sajudis, and Algirdas Brazauskas, a former Communist, was elected president in 1993. Also in 1993, the last Russian troops were withdrawn, and Lithuania signed a free-trade agreement with fellow Baltic states Estonia and Latvia.
Valdas Adamkus, an emigrant from the United States, was elected president in 1998, but lost in a runoff in 2002 to Liberal Democratic party candidate Rolandas Paksas. Charges of corruption and links to Russian organized crime led the parliament to initiate impeachment proceedings against Paksas in Dec., 2003, and he was narrowly removed from office the following April. Parliament speaker Arturas Paulauskas became acting president. The same month Lithuania joined NATO; both events and others led to tensions with Russia in early 2004. Lithuania also became a member of the European Union in 2004. In new elections in June, 2004, Adamkus won a second term as president, after a runoff. In October former president Paksas was acquitted of leaking state secrets, one of the three charges on which he was impeached. Adamkus was succeeded as president by Dalia Grybauskaite, who had been serving as the European Union's budget commissioner and ran as an independent; elected in May, 2009, she became the first woman to hold the presidency.