The background of the occupation of the Baltic states covers the period before the first Soviet occupation on 14 June 1940, stretching from independence in 1918 to the Soviet ultimatums in 1939–1940. Lithuania, Latvia, and Estonia gained independence in the aftermath of the Russian revolutions of 1917 and the German occupation which in the Baltic countries lasted until the end of World War I in November 1918. All three countries signed non-aggression treaties with the Soviet Union in the 1920s and 1930s. Despite the treaties, in the aftermath of the 1939 German–Soviet pact, Estonia, Latvia and Lithuania were occupied, and thereafter forcibly incorporated into the Soviet Union, in 1940.
Independence process
The Russian Empire acquired the Baltic areas as autonomous Duchies administered by Baltic German nobility via the Treaty of Nystad in 1721 and Courland in 1795. In 1914, World War I broke out and by 1915 German armies had occupied Lithuania and Courland incorporating the areas into Ober Ost. As the Russian Empire began to collapse, independence movements sprung up on many regions. After the 1917 October Revolution in Russia, Baltic political leaders attempted to establish the independent states of Estonia, Latvia and Lithuania; however, German control continued throughout the area until early 1918. Later in 1918, the area was drawn into the Russian Civil War and proclamations of independence were issued in Lithuania on 16 February, in Estonia on 24 February and in Latvia on 18 November 1918.
Between years of 1918–1920, the bolsheviks tried to establish Soviet republics in the Baltic area. In November 1918 the Red Army conquered Narva. They proclaimed the Commune of the Working People of Estonia, but it was able to function only for six weeks. In December, the Latvian communists controlled Riga and proclaimed the Latvian Socialist Soviet Republic. In May 1919, the communist control ended when the city was taken by combined German, Latvian and White Russian troops.
By 1920, German troops had withdrawn and the Russian Civil War was in its final phase. Consequently, the Baltic states signed peace treaties with Soviet Russia. Estonia signed the Treaty of Tartu on 2 February, Lithuania signed the Soviet–Lithuanian Peace Treaty on 12 July and Latvia signed the Latvian–Soviet Peace Treaty on 15 August 1920. In 1920, all three Baltic states adopted constitutions including universal suffrage, a multi-party system and parliamentary with a president. However, the communists were prohibited from participation in politics.
Diplomacy in the 1920s and early 1930s
Baltic states seek security guarantees
The Bolsheviks could not prevent the independence of the Baltic states, but the West had to be persuaded to accept it. By 1921 Lithuania, and by 1922 Estonia and Latvia, all obtained de jure international recognition. All three states joined the League of Nations in 1921. The Baltic states begin to build a regional alliance system with their neighbours in Scandinavia and eastern Europe. In the south, Poland was reconstituted with consolidation of territories from Germany and Russia. Furthermore, in summer 1920, Lithuania cooperated with Bolsheviks trying to seize Vilnius, which poisoned Lithuanian relations with their neighbours. In the north, Finland had also been under Russian control from 1809 until its independence in 1918, but the Finns looked to Scandinavia rather than towards the Baltic states. In the west, Sweden followed a policy of neutrality, but during the 1920s, it took a more active regional role.
Between 1917 and 1934, the Baltic states worked to improve security, and unsuccessfully attempted to build a regional bloc stretching from Scandinavia to Romania. The Estonians and Latvians concluded a military convention in 1923, which Lithuania joined in 1934. Further, the Estonians and Latvians held a joint military exercise in 1931, but it was not repeated and collaboration remained a dead letter thereafter. However, the Finns and the Estonians had secret military exercises in the early 1930s, reconstructing the tsarist naval batteries. Finally in 1934, the three Baltic states reached the Baltic Entente agreement.
In spite of the Vilnius issue, the Baltic states were open to the Polish option. The Warsaw Accord was signed in March 1922 by Finland, Poland, Estonia and Latvia, but the Finnish parliament failed to ratify it.