Russian Expeditionary Force in France

The Russian Expeditionary Force (REF; Russian: Экспедиционный корпус Русской армии во Франции и Греции, lit. 'The Russian Army Expeditionary Corps in France and Greece'; French: Corps Expéditionnaire Russe en France) was a World War I military force sent to France and Greece by the Russian Empire. In 1915, the French requested that Russian troops be sent to fight alongside their own army on the Western Front.

Source: Wikipedia — Russian Expeditionary Force in France (CC BY-SA 4.0)