 Details from the regiment were placed on service on 26 August 1939 and then placed on active service on 1 September 1939 as the Irish Regiment of Canada (Machine Gun), CASF (Details), for local protection duties.Those details called out on active service disbanded on 31 December 1940.The regiment mobilized the Irish Regiment of Canada (Machine Gun), CASF for active service on 24 May 1940.