Administration of armies has been sadly neglected in historical studies but the ability of the AIF to develop an efficient system of administration and to fit into the equally efficient British system, had much to do with the success of the AIF, especially late in the war. The various Empire governments had made some preparations for an alliance system of fighting in the event of a major war, but in practice these needed a great deal of adjustment. This thesis examines the manner in which the dominions and Britain planned for a possible war and the way in which changes had to be made in practice. It examines the manner in which the AIF developed a system and the many facets of this system, which had developed a remarkable degree of efficiency by the end of the war. Because the AIF and CEF were so alike in size, composition and in the problem they faced, a recurring theme of the thesis is a comparison between the two. It embraces the following: a. Prewar preparation for a combined empire army. b. The organisation of the administrative system of the AIF and the manner this improved through the war. c. The organisation and problems of the CEF administrative system d. The development of a system of capitation to pay for the services supplied to the AIF and CEF. e. Supply of equipment. f. Manner in which both forces worked to maintain their forces. g. The manner in which both forces catered for the needs of the individual soldiers. h. Supply in the field i. Medical administration in the AIF j. The administration in the AIF k. The administration of discipline in the AIF l. The demobilisation of the AIF.