when did the coast guard became a military branch
United States Coast Guard The Coast Guard as established January 28, 1915, shall be a military service and a branch of the armed forces of the United States at all times. The Coast Guard shall be a service in the Department of Homeland Security, except when operating as a service in the Navy.[24]
Service number (United States Armed Forces) Service numbers were eventually phased out completely by the social security number; the Army and Air Force converted to social security numbers on 1 July 1969, the Navy and Marine Corps on 1 January 1972, and the Coast Guard on 1 October 1974.[4] Since that time, social security numbers have become the de facto military service number for United States armed forces personnel.