Explanation: The Czechoslovak Legion was a military formation during WW1 that was organized against the Central Powers, in the hopes of earning Triple Entente support for an independent Czechoslovakia.

After the Bolshevik coup of the democratic socialist government of Russia, Russia pulled out of WW1, resulting in the Czechoslovak legionaries in Russia needing to evacuate to continue the fight. Unfortunately, as the ports of European Russia were largely constrained by the positioning of the Central Powers, the decision was made to evacuate the legionaries by the Pacific port of Vladivostok.

The Bolsheviks and Czechoslovaks made an agreement to allow this, under the condition that the Czechoslovaks surrender most of their heavy equipment. The Czechoslovaks agreed. Despite this, the Bolsheviks decided to turn on the Czechoslovaks anyway, attempting first to arrest them, and then to kill them.

Thus began a year-long involvement in the Russian Civil War as the Czechoslovak Legion attempted to cross the country to Vladivostok, evacuation, and, by the time they got to Vladivostok, the safety of a post-WW1 peace and a newly independent Czechoslovakia.

They acquitted themselves very well.