This series comprises a range of sensitive case files covering issues mainly to do with national security. From World War 1, the files were compiled by the Commonwealth Police Force, the South Australian Investigation Branch and the Commonwealth Investigation Service. The files contain, inter alia, translations and original correspondence, records of interrogation and appeal hearings, information garnished from informers and surveillance, aliens, enemy sympathisers, subversive elements, Revolutionaries, Bolshevists, Fascists, enemy espionage, European Fascist parties, Anti-Semitism, reports on internment and internees from both World Wars, cults, sects, Irish National Association activities, propaganda, information on deportations, applications for naturalisation and requests for information from the Immigration authorities.

The series also contains confiscated material in the form of photographs, postcards, maps, posters etc. There was a good deal of additions to files from previous series onto this one.

The 0.18m held by National Office consists of a photocopy of file number SA16752 in D1915/2. It is a reference copy; the original was returned to the German Foreign Office in 1995.

D1915 was relocated from South Australia to the ACT in November 2021.