Why did Russia withdraw from World War 1?
The shortage of supplies and food and the trouble of their own country which lead to the Russian Revolution in 1917.
Russia started having a civil war and Russia couldn't take any more loss as it was.
More in depth, Russa was having a revolution to overthrow the Tzar, who was keeping Russia in the war, though they were losing many men. And morale was very very low. So people were desperate for someone new to rule the country. So Lenin, the communist came in and promised Peace, Land, and Bread. Peace meaning, withdrawal from the war. (which everyone wanted). And by bread he meant... bascially to earn when you work. Implemented a minimum wage, maximum work hours.
Russia withdrew because they had their own problems to worry about, and were in no shape to get dealing wiht the rest of the word