For centuries, the southeastern shore of the Baltic Sea was inhabited by various Baltic tribes. In the 1230s, the Lithuanian lands were united by Mindaugas I, the King of Lithuania, and the first unified Lithuanian state, the old kingdom, was created on 6 July 1253. During the 14th century, the Grand Duchy of Lithuania was the largest country in Europe; present-day Lithuania, Belarus, Ukraine, and parts of Poland and Russia were the territories of the Grand Duchy. With the Lublin Union of 1569, Lithuania and Poland formed a voluntary two-state union, the Polish–Lithuanian Commonwealth. The Commonwealth lasted more than two centuries, until neighboring countries systematically dismantled it from 1772–95, with the Russian Empire annexing most of Lithuania's territory.
As World War I neared its end, Lithuania's Act of Independence was signed on 16 February 1918 declaring the establishment of a sovereign State of Lithuania. Starting in 1940, Lithuania was occupied by the Soviet Union and then liberated in 1941. On 11 March 1990 Lithuania became the first of many Eastern European states to reintroduce democracy.
As a result of the Great Retreat during the World War, Germany occupied the entire territory of Lithuania and Courland by the end of 1915. A new administrative entity, Ober Ost, was established. Lithuanians lost all political rights they had gained: personal freedom was restricted, and at the beginning the Lithuanian press was banned. However, the Lithuanian intelligentsia tried to take advantage of the existing geopolitical situation and began to look for opportunities to restore Lithuania's independence. On 18–22 September 1917, the Vilnius Conference elected the 20-member Council of Lithuania. The council adopted the Act of Independence of Lithuania on 16 February 1918 which proclaimed the restoration of the independent state of Lithuania governed by democratic principles, with Vilnius as its capital. The state of Lithuania which had been built within the framework of the Act has lasted since 1918.
To prevent being incorporated into the German Empire, Lithuanians elected Monaco-born Duke Wilhelm Karl of Urach as King in June 1918. The following month the first Provisional Constitution of Lithuania was adopted and the first government of Prime Minister Antanas Smetona was organized. At the same time, the army and other state institutions began to be organized. Lithuania's independence was recognised internationally at the Lausanne Peace Conference in 1919 but not its territory. As a result of the staged Suwałki Agreement in October 1920, Lithuania took control of the Marijampolė Region from Poland and divided the Vilna Governorate with Belarus securing their capital. Relations with Poland remained particularly tense and hostile for the entire interwar period.
On 15 May 1920, the first meeting of the democratically elected constituent assembly took place. The documents it adopted, i. e. the temporary (1920) and permanent (1922) constitutions of Lithuania, strove to regulate the life of the new state. Land, finance, and educational reforms started to be implemented. The University of Lithuania was opened. All major public institutions had been established. As Lithuania began to gain stability, more foreign countries started to recognize it.
On 17 December 1926, a military coup d'état took place resulting in the replacement of the democratically elected government with a conservative authoritarian government led by Antanas Smetona. Augustinas Voldemaras was appointed to form a government. The so-called authoritarian phase had begun strengthening the influence of one party, the Lithuanian Nationalist Union, in the country. In 1927, the Seimas was released. A new constitution adopted in 1928, which consolidated executive powers. Gradually the opposition parties were banned, the censorship was tightened, and the rights of national minorities were narrowed.
On 15 July 1933, Steponas Darius and Stasys Girėnas, Lithuanian pilots, emigrants to the United States, made a significant flight in the history of world aviation. They flew across the Atlantic Ocean, covering a distance of 3,984 miles (6,411 kilometers) without landing, in 37 hours and 11 minutes (107.1 mph). In terms of comparison, as far as the distance of non-stop flights was concerned, their result ranked second only to that of Russell Boardman and John Polando.
The country had a Western standard of living with sufficiently high salaries and low prices. At the time, qualified workers there were earning very similar real wages as workers in Germany, Italy, Switzerland and France, the country also had a surprisingly high natural increase in population of 9.7 and the industrial production of Lithuania increased by 160% from 1913 to 1940.
The situation was aggravated by the global economic crisis. The purchase price of agricultural products had declined significantly. In 1935, farmers began strikes in Suvalkija and Dzūkija. In addition to economic ones, political demands were made. The government cruelly suppressed the unrest. In the spring of 1936, four peasants were sentenced to death for starting the riots.