Commonwealth of Australia Act No. 20 of 1903 provided, per s. 8, that the Governor-General may appoint any part of the Commonwealth to be a Military District, divide any Military District into sub-districts and appoint an officer to be Commandant of any Military District. In 1939, with war a very real possibility, the Cabinet, Gavan Long reports, sought some analysis of the position of the Australian Army. (Australia in the War of 1939-1945; Volume I, "To Benghazi" by Gavan Long, 1952, p. 27). The Government appointed Major General Squires of the British Army, to the newly revived post of Inspector-General to make an "authoritative report" on the Army. 

The report presented to the Parliament recommended that the existing district bases (each coinciding more or less with one or other of the States) and the infantry and cavalry divisions be regrouped into four "Commands" - Northern (Queensland), Eastern (New South Wales), Southern (Victoria, Tasmania and South Australia) and Western, with an independent garrison at Darwin - each of which would be responsible for the training and, in war, for the operations of the formations in its area. (Ibid p. 28)
The Government acted on the advice given it. Commonwealth of
Australia Act No. 13 of 1939, the Defence Act 1939, assented to on 21 June 1939, repeated (per. S. 5(1) s. 8 of the Principal Act and inserted the following:-
"s. 8 (b) The Governor-General may appoint any part of Australia to
          be a Command or Military District".
This was followed by an Amendment to the Australian Military
Regulations. The Australian Military Regulations 1927 (Statutory Rules, No. 149 of 1927) provided, per Regulation 41, that the 2nd Military District would be approximately equivalent in geographical area, to the State of New South Wales. On 25 July 1939 the Government promulgated an amendment to Regulation 41. Regulation 41A of Statutory Rules No. 58 of 1939, provided that 2nd Military District would become Eastern Command.  (Commonwealth of Australia Gazette 1939 (p. 1350) No. 19, of 27th July 1939).

Headquarters, Eastern Command came into existence on 13 October 1939 after the Governor-General had approved the appointment of Colonel V.A.H. Sturdee CBE DSO as General Officer Commanding Eastern Command and Local Major General and Temporary Lieutenant-General on 11 October 1939, effective from the 13th. (Executive Council Minute No. 322) (Commonwealth of Australia Gazette 1939, (p. 2130) No. 104, of 12th October).
Eastern Command was succeeded by New South Wales Lines of
Communication Area, under the Command of Major-General A.C. Fewtrell, CB, DSO, VD on 15 April 1942.
 

Historical agency address
Victoria Barracks, Paddington NSW
Legislation administered
Commonwealth of Australia Act No. 20 of 1903, Defence Act 1903-1941
Australian Military Regulations, Statutory Rules No. 49 of 1927 Australian Military Regulations 1939, Statutory Rules No. 58 of 1939

Agency controlled unregistered

Military Units and Military Establishments (subject to research)