World War I in eastern Europe and the Russian Revolution (31 May 1918)
Historical Map of Russia
Large numbers of Czechs and Slovaks had joined the Russians during the War, forming a Czechoslovak Legion to fight for the independence of their homeland (then part of Austria-Hungary). After the Soviets made peace with the Central Powers, they agreed to let the Czechoslovaks travel to France via Siberia to continue their struggle. However German pressure first slowed the evacuation and then led to a Soviet attempt to disarm the Legion. The result was a disaster for the Soviets as the Czechoslovaks revolted and began occupying cities along the Trans-Siberian Railway.