The Canadian Siberian Expeditionary Force (also referred to as the Canadian Expeditionary Force (Siberia) or simply C.S.E.F.) was a Canadian military force sent to Vladivostok, Russia, during the Russian Revolution to bolster the allied presence, oppose the Bolshevik revolution and attempt to keep Russia in the fighting against Germany. Composed of 4,192 soldiers and authorised in August 1918, the force returned to Canada between April and June 1919. The force was commanded by Major General James H. Elmsley. During this time, the C.S.E.F. saw little fighting, with fewer than 100 troops proceeding "up country" to Omsk, to serve as administrative staff for 1,500 British troops aiding the anti-Bolshevik White Russian government of Admiral Alexander Kolchak. Most Canadians remained in Vladivostok, undertaking routine drill and policing duties in the volatile port city.
The Marine Cemetery in Vladivostok, a Commonwealth War Graves Commission site, contains the graves of 14 Canadians alongside British, French, Czecho-Slovak and Japanese troops who died during the Siberian Intervention and a monument to Allied soldiers buried in various locations in Siberia. The Commonwealth portion of the cemetery was neglected during the Soviet era; a Canadian naval vessel restored the cemetery in the 1990s. In 1996 a Canadian squadron of warships visited Vladivostok. During the visit sailors from HMCS Protecteur, assisted by members of the Russian Navy, replaced headstones and generally repaired the graves of Canadians buried in a local cemetery.
Allied intervention in Siberia was driven by a mix of motivations. Prior to the Armistice in the fall of 1918, there was a genuine concern that military supplies would be used – directly or indirectly – by the Germans, and that access to the natural resources of the Russian Far East (over the Trans-Siberian Railway) could tilt the outcome of the battles on the Western Front. There was outright hostility to the Bolsheviks, particularly on the part of Winston Churchill, and national trade and (perceived) economic interests on the part of each of the governments. The case of the Czechoslovak prisoners of war, who had been offered safe passage by the Soviet government and then threatened with internment in "concentration camps" aroused sympathy on the part of many governments, particularly the United States. When the Czech troops attempted to battle their way out of Russia - eventually controlling much of the Trans-Siberian railway - various Western governments chose to intervene.