Answer: Lenin concluded a separate peace with Germany.
Step-by-step explanation:
The Russians had been involved in the first World War as part of the Allies but were suffering heavy defeats at the hands of the Germans. A Revolution in 1917 ended the Tsarist government but the new government made the mistake of continuing the war.
This led to more defeats and the Bolsheviks came to power. Lenin knew that he simply had to end the war and after attempting to make the Germans negotiate with less harsh terms, eventually accepted and signed the humiliating treaty of Brest-Litovsk thereby concluding a separate peace with Germany.