The Department of Defence [I], one of the original Commonwealth departments, was created on 1 January 1901. Under the terms of the Constitution Act 1900, the Commonwealth took over control of naval and military defence matters from the States on 1 March 1901. The responsibilities of the Minister for Defence as set out in the earliest extant Administrative Arrangements Orders probably prepared in 1901 were:
 
. Naval and Military defence
. Control of railway transport for defence
 
which were legislative powers of the Commonwealth as set out in the Constitution Act, section 51 (vi) and (xxxii) respectively.
 
For four years from 1901 the land forces were administered by a General Officer Commanding under the ministerial headship of the Minister for Defence; the naval forces were likewise administered by a Naval Officer Commanding under the Minister. When the Council of Defence was established in 1905, a Military Board and a Naval Board were constituted and took over the administration of the Commonwealth military forces and naval forces, thereby ensuring continuity of policy and administration. In the Administrative Arrangements Orders of 4 April 1912 published in the Commonwealth Gazette of 13 April 1912, the matters dealt with by the Department were expanded to include:
 
. Naval and Military Factories and Workshops.
 
On 12 July 1915 the Department of the Navy [I] (CA 13) was created and took over responsibility for all naval matters from the Navy Office [I] (CA 575) within the Department of Defence [I] . As set out in the next full Administrative Arrangements Orders of 22 September 1915 the Department of Defence [I] became responsible for the administration of the War Precautions Repeal Act 1914-1915 and the matters it dealt with were expanded to the following:
 
. Administration of Territory in Military Occupation
. Control of Railways with respect to Transport for Defence purposes
. Factories and Workshops for Defence purposes
. Land Defence of the Commonwealth and Organisation for War
. Provision of Troops for active service abroad
. Royal Military College
 
In July 1917 a Royal Commission on Navy and Defence Administration (CA 2289) was established to enquire into and report inter alia upon monies administration generally within the Defence Department, including contracts and supplies. The Commission's recommendations, which were approved by the Government in February 1918, were that the business administration of the Department should be placed under the control of a "Board of Business Administration" consisting of three business men, with subordinate business boards in each State, and that an administrative inspector-general should be appointed. The Business Board (CA 183) was made responsible for the purchase of supplies, for the management of defence factories, for the transport services and for financial and stores accounting. The Board was terminated in March 1920. By 1921 as set out in the Federal Guide (p 30), the Department of Defence was responsible for those matters as set out in the September 1915 Administrative Arrangements Orders with the addition of 'air navigation'.
 
There were seven factories established under the authority of the Defence Act in connection with the Defence Department:

. the Commonwealth Harness, Saddlery and Leather Accoutrements
  Factory at Clifton Hill, Victoria was opened in September 1911;

. the Cordite Factory at Maribyrnong where cordite was manufactured
  for the cartridges required for military purposes; 

. the Clothing Factory (CA 627) at South Melbourne which supplied the
  whole of the uniform clothing required for the Defence forces and
  the Postmaster-General's Department; 

. the Small Arms Factory at Lithgow (CA 626) which was opened on 1
  June 1912; 

. the Commonwealth Woollen Cloth Factory at Geelong which commenced
  operations at the end of 1915; 

. a Commonwealth Factory was established in September 1918 at
  Bulimba, Brisbane for the manufacture of acetate of lime; and 

. a Commonwealth Factory was established at Caulfield, Victoria for
  the manufacture of artificial limbs.
 
Acts administered by the Department by 1921 (Federal Guide, p 30) were:  

. Air Navigation Act
. Deceased Soldiers' Estates Act
. Defence Act
. Defence (Civil Employment) Act
. Matrimonial Causes (Expeditionary Forces) Act.
 
On 21 December 1921, the Department of Defence [I] and the Department of the Navy [I] (CA 13) were amalgamated to form the Department of Defence [II] (CA 19).
 
Ministers for the Department of Defence [I] were:
 
  1 Jan 1901 - 10 Jan 1901: Sir James Robert Dickson
 10 Jan 1901 - 10 Aug 1903: Sir John Forrest
 10 Aug 1903 - 24 Sep 1903: Senator James George Drake
 24 Sep 1903 - 27 Apr 1904: Austin Chapman
 27 Apr 1904 - 17 Aug 1904: Senator Anderson Dawson
 18 Aug 1904 -  5 Jul 1905: James Whiteside McCoy
  5 Jul 1905 - 24 Jan 1907: Senator Thomas Playford
 24 Jan 1907 - 13 Nov 1908: Thomas Thomson Ewing
 13 Nov 1908 -  1 Jun 1909: Senator George Foster Pearce
  2 Jun 1909 - 29 Apr 1910: Joseph Cook
 29 Apr 1910 - 24 Jun 1913: Senator George Foster Pearce
 24 Jun 1913 - 17 Sep 1914: Senator Edward Davis Miller
 17 Sep 1914 - 21 Dec 1921: Senator George Foster Pearce.
 
Secretaries to the Department of Defence [I] were:
 
  1 Jul 1901 - 28 Feb 1910: Sir Robert Collins
  1 Feb 1910 - 25 Feb 1918: S A Pethebridge
  1 Feb 1918 - 21 Feb 1921: T Trumble
 
Further research is required to determine in more detail the
relationship between the Department of Defence [I] and the military and naval forces.
 

Sources 

1. The early Administrative Arrangements Orders were not gazetted. 
   The earliest extant Orders so far identified are those in the 
   papers of Barton held in the National Library of Australia (Other
   Political Papers, 1892-1911: MS 51, series 7, item 1028). They
   possibly date from 1901.
2. Commonwealth Gazette No 1, 1 Jan 1901, p 41; No 9, 20 Feb 1901, 
   p 21; No 38, 30 July 1901, p 127; No 26, 13 Apr 1912, p 477;  
   No 114, 22 Sep 1915, p 2406; No 99, 24 Dec 1921, p 2403 
3. Federal Guide, 1921, p 30
4. Commonwealth of Australia Year Book No 12, pp 999, 1000, 1012
   and 1018.
5. Public Service Board Annual Report 1973, pp 122-126
6. Colin A Hughes & B D Graham, A Handbook of Australian
   Government and Politics 1890-1964, ANU Press, Canberra, p 39
7. Sir John Allison: "The Contribution of Advisory Bodies to
   Defence" in Public Administration Journal Vol XXV, No 1, March
   1966
Historical agency address
1901-?1921: Victoria Barracks, St Kilda Road, Melbourne
Legislation administered
Creation: Commonwealth of Australia Constitution Act 1900, Section 69; Prime Minister's Executive Council Minute No 1 of 1901 
Abolition: Executive Council Meeting No 70 (Prime Minister's Department Minute No 317), 21 December 1921