Dominion Police
The Dominion Police, although the federal police of Canada, was mainly active in the Eastern Canada region, while the Royal Northwest Mounted Police handled the expansive and sparsely populated Northwest Territories of Western Canada. In May 1918, the 969-member Dominion Police was reassigned under the Department of Militia and Defence and became a civilian wing of the Canadian Military Police Corps (CMPC). In the early 1900s, the Royal Northwest Mounted Police had declined as the Northwest Territories was divided into new provinces and territories, and due to the general unpopularity of the force for conduct during industrial disputes such as the Winnipeg General Strike. On 1 February 1920, the civilian members of the CMPC, including the Dominion Police, were merged with the Royal Northwest Mounted Police to form the Royal Canadian Mounted Police as the new federal police force of Canada, and the CMPC was disbanded on 1 December 1920.
RCMP Security Service
In 1950, the Royal Canadian Mounted Police's Special Branch was formally established to conduct its counterintelligence operations. Prior to that, the branch was a component of the RCMP's Criminal Investigation Branch, where political security operations and criminal investigations were not distinct before 1936. The Mounties carried out extensive security service work since the force was reconstituted in 1920, when it merged with the Dominion Police and became the federal police agency solely responsible for national security. Between the wars, this work was overwhelmingly directed at the Communist Party and labour and the left more generally.