This series consists of Defence correspondence classified as secret between 1939 and 1945, with the majority of records dating from the period 1939 to 1942. Subjects covered include: 

* Establishments, organisation and composition of combative and non-combative units; 
* Nominal rolls of re-enforcement and replacement units; 
* Officer promotions, placement and movements; 
* Issues of servicemen's pay; 
* Unit establishment costs and expenditures; 
* Headquarters, bases and unit financial arrangements; 
* Administration, manufacture and distribution of provisions, stores, equipment, munitions and other ordinance;
* Reports from AIF overseas bases and offices; 
* Weekly intelligence reports; 
* War Cabinet and War Office minutes; 
* Order of Battle correspondence; 
* Inter-departmental correspondence between the Departments of the Army and the Navy; 
* Troopship movements; 
* Ships medical reports; 
* Ships inspection reports; 
* Enemy action reports; 
* Liaison letters from prominent military and political individuals.

Files were raised in accordance with a multiple number system by which primary and secondary subject classification numbers were allocated to registered correspondence. The base paper of each file was registered with a square 'secret' stamp, subsequent correspondence being allocated the same number within a round 'secret' stamp.  This system seems to have been abandoned in later years with each paper being allocated the pertinent file number in the upper right corner only.

Administrative information
 
The following data was keyed from the paper documentation:
Form number:              CA 11
Creating department:      Army, Central Office
Transferring department:  Defence [III]
Archives file number:     RWM30/2/27
 
These are part of the series, CRS B1846, Secret correspondence files, but have not been physically converted to CRS B1846. The records in this series should be called for by the MP729/7 number.