Why did Russia leave World War I?

Social and economic chaos led to revolution and the fall of czardom in Russia in 1917. In 1918, the Bolshevik government signed a peace treaty with Germany (the Treaty of Brest-Litovsk). It got Russia out of the war, ending the Eastern Front to the dismay of France and Britain. The Bolsheviks wanted to consolidate power because it was seen as a priority over the continuation of a conflict they judged to be an "imperialist" war. The peace of Brest-Litovsk supposed colossal territorial losses for Rusia: they handed over Finland, Poland, Ukraine, the Baltic republics and Transcaucasia to the Central Powers; Russia ceded one third of the tsarist empire's population, one-third of its agricultural land and three-quarters of its industries.

Bolsheviks.

Explanation:

A revolutionary group that became a communist party and took over Russia. They signed a treaty and removed themselves from the war of WWI.