When the First World War started, they found themselves in the battle field since the German-Russian frontier ran from Lithuania to Poland. As a result of the Russian defeats, the Germans invaded and occupied some Baltic territories between 1914 and 1917. As it is shown in the map, the green line in the map represents the German advances in 1917, while the little squares represent the armies of the two Central Empires (yellow and blue) and Russia (red) at the eve of the Russian Revolution: Lithuania and the southern part of Latvia (Courland and southern Livland) were occupied by the Germans, while the northern part of Livland and Estonia (Estland) were still part of the Tsardom.
On 7 November 1917, a small but well organized Marxist party, the Bolsheviks – guided by the famous socialist leader Vladimir Lenin - took the control in Petrograd, toppling the provisional government of Kerensky. In some areas of the empires, Bolsheviks had a good consensus, especially in Estonia and in the free Latvian territories. Here, they were backed by the industrial proletariat and the army, composed mainly by Russians.
The constant advance of German troops and the Bolshevik coup d’état prompted the Estonian and Latvians parties to change aim: from a democratic autonomy in a Russian democratic federative state to the full independence. In the mid of November, the Estonian Provincial Assembly and the Latvian Provisional National Council affirmed to be the sole authorities of their respective nations.
In 1918, the Bolshevik seizure of power provoked the reaction of many groups, especially those who desired the return to the status quo, like the monarchists and a civil war raged across the war-torn Russia. The Estonian and Latvian Bolsheviks, although they were popular and controlled their provinces, did not enjoy a good support as they showed no tolerance towards the other parties. Lastly, they were forced to leave soon the Baltic because of the unstoppable march of the German army.
Lithuanians were constrained to act following the German dispositions as their country was completely at the mercy of Berlin. In December 1917, their National Committee, the Taryba, declared an independent Lithuania, strongly connected with the Second Reich. They tried to reach a greater degree of freedom, proclaiming their independence on 16 February 1918.
This declaration resulted in the restoration of an independent Lithuania, since in the Middle Age there was already a Lithuanian state. However, the signature of the Treaty of Brest-Litosvk (3 March, 1918) cancelled this project, ceding the Baltic provinces to Germany.
The Estonian leaders proclaimed the Estonian independence on 24 February 1918 before the arrival of the German troops in Tallinn. The Baltic provinces suffered the German rule because it was severe and the economic resources were all taken to sustain the German war effort. In Latvia the declaration of independence was carried out in November 1918, due to the war and the political situation.
These declarations of independence, whose dates are remembered to this day in the three Baltic countries, did not immediately sanction the birth of three independent states. As it happened to Poland, Lithuania, Latvia and Estonia had to fight amidst the Russian Civil War to obtain their independence because nor Bolsheviks neither White Russian army were intentioned to grant them the independence.
Following two years of intense conflict, by 1920 the three Baltic countries were completely free and signed the peace treaties with the Soviet Union who granted them full independence. The Entente powers were nevertheless reluctant to recognise a full independence because of its alliance with Russia and the White Russian movement. Baltic States continued to press them for full recognition and they could reach it in 1921 for Estonia and Latvia, 1922 for Lithuania.
Finally, the Baltic countries entered the League of Nations in September 1921, becoming members of the new international community.