[1][6][7] On 6 August 1914, Details of the 20th Border Horse were placed on active service for local protective duties.
[2] On 10 August 1914, the 6th Battalion (Fort Garrys), CEF, was authorized for service.
On 20 January 1915, the battalion formed the nucleus of the Remount Depot.
On 6 March 1915, the remainder of the battalion were absorbed by the Canadian Cavalry Depot, CEF, to provide reinforcements for the Canadian Corps in the field.
[2][8] On 15 March 1920, as a result of the Otter Commission and the following post-war reorganization of the militia, the 20th Border Horse was Redesignated as The Border Horse.