This series records the more important activities of the
 Department of Defence rather than routine matters of military administration. Much information on such topics as Australian defence and foreign policy, particularly between the wars, and Australia's appreciation of her position in the world, may be found. Internal defence schemes and Australian society during World War I are other subjects covered. In general, the emphasis ison military rather than naval matters. Some of the files in
this series are in their original file covers, others have
been grouped into manila folders. Some file covers are marked "Dept. of Defence - Secretariat" and "Dept. of Defence -
Military Board". The files are part of a classified 3-number
series (1801-2100) which was introduced in 1906 for both the
security classified and general correspondence. According to
Army Archives, the classified and general correspondence series ran concurrently until 1913 when the unclassified series adopted a different system. The former was distinguished from the latter by the use of "secret" stamps. It seems likely that the two
series were held separately - possibly the security classified correspondence was kept in a separate part of the central
registry. There are references on file to secret documents
held in the "strong room". Down-grading of files was carried
out by an officer of the rank of colonel or above. Secret
stamps were crossed and initialled. Some files in this series were declassified around 1960.
Rectangular and oval registry stamps appear on most files. The stamps have various headings, e.g. "Defence / Secret", "Defence / Central Administration", "Defence / Confidential Records."
Several prefixes appear before the file registration, the most common being "SC" (secret and confidential?) and "S" (secret?). Many of the folios are marked with an "S" followed by a number - this appears as well as the 3 number registration and is
usually on the top left side of the page. These numbers were
allocated to secret memos arising out of the correspondence.
The memos were numbered 1 - .... for each year and were registered in the subsequent action column of the L 14's against
the folio to which they related.
In most cases the files have been given the number of top or last folio - i.e. when there were no subsequent papers the file was closed. Registration numbers were supposed to be written on
every folio of every paper registered and on all enclosures
except in the case of printed or bulky enclosures. The files
indicate that this practice was not strictly adhered to. Outward letters were numbered serially as were copies kept by the
Department. Inward letters were passed directly to the officer responsible for answering them.
 

Subsequent series unregistered

Secret correspondence files, multiple number series (class 401), 1936-1945