In 1918, the world had been at war for four years. The First World War involved the great powers of Europe, as well as other countries such as the United States, Japan and the Ottoman Empire. The war caused millions of deaths, destruction and suffering.

In Russia, the war also provoked a revolution. In 1917, the Bolsheviks, led by Vladimir Lenin, overthrew Tsar Nicholas II and established a socialist government. They promised to end Russia's participation in the war, which was unpopular with most Russians.

To fulfill this promise, the Bolsheviks sent a delegation to negotiate peace with the Central Powers (Germany, Austria-Hungary, Bulgaria, and the Ottoman Empire), who were Russia's enemies in the war. The leader of the delegation was Leon Trotsky, the people's commissar for foreign affairs.

Negotiations began in December 1917, in the city of Brest-Litovsk, located in present-day Belarus, near the border with Poland. The Central Powers demanded that Russia cede large territories, such as Ukraine, Poland, Belarus, the Baltic provinces and the Caucasus provinces. These lands represented a significant part of Russia's population, industry, natural resources and railways.

Trotsky tried to postpone the negotiations, hoping that a socialist revolution would take place in the Central European countries and change the balance of forces. He also wanted to consult with Russia's other socialist parties, who were against handing over territories. However, the Central Powers lost patience and launched a new military offensive against Russia in February 1918.

Faced with the threat of an invasion, Trotsky decided to declare that Russia was exiting the war, without signing a formal treaty. He hoped this would be enough to stop the Central Powers, but they continued to advance and occupy more Russian territory.

Finally, on March 3, 1918, the Bolsheviks were forced to sign the Treaty of Brest-Litovsk, which confirmed the demands of the Central Powers. Russia lost about a third of its population, more than half of its industrial land, almost all of its coal fields and a quarter of its railways. The treaty also recognized the independence of Finland and Ukraine, which had separated from Russia during the revolution.

The Treaty of Brest-Litovsk was very controversial in Russia, as it was seen as a betrayal of national interests and socialist ideals. Many Russians felt humiliated and outraged by the loss of territories. Some political parties, such as the Left Social Revolutionaries, opposed the treaty and rebelled against the Bolsheviks. The signing of the treaty also gave a motive to the counter-revolutionary movements, known as Whites, who fought against the Bolsheviks in the Russian Civil War, which lasted until 1921.

The Treaty of Brest-Litovsk was annulled by the Armistice of November 11, 1918, which ended the First World War and marked the victory of the Allies (France, Great Britain, the United States and others) over Germany. By the Treaty of Versailles, signed in 1919, Germany was obliged to return the territories it had gained from Russia through the Treaty of Brest-Litovsk. The Bolsheviks, who became the leaders of the Soviet Union, attempted to regain power in territories lost during the Russian Civil War, with mixed results. They were defeated in the wars of independence of the three Baltic countries and the war against Poland, but managed to invade Azerbaijan, Armenia, Georgia and Ukraine.

The Treaty of Brest-Litovsk was one of the most important events in the history of Russia and Europe in the 20th century. He showed the consequences of revolution, war and diplomacy in transforming borders, identities and relationships between people.