Which event led russia to withdraw from world war i and surrender a significant amount of territory to germany

On the 16th of April 1917, The leader of the Bolshevik Party, Vladimir Lenin returned to Russia from Exile.

Soon after he started negotiations with the Germans which lasted nearly 2 months. By the end of the negotiations, the Treaty of Brest-Litovsk was signed in March, 1918.

The treaty effectively ended Russia's participation in the War. Russia ceded the Baltic States to Germany, which became the latter's vassal states. 

Russia also ceded its province of Kars Oblast to the Ottoman Empire and had to recognized the Independence of Ukraine.