Lieutenant Blaxland postulates that over the last two centuries, since the introduction of the concept of 'divisions' by Napoleon, armies have been shaped in response to the interaction of four main factors. These are: the nation's strategic outlook and perceived combat roles, the economic determinants of finance and manpower, the impact of technological developments on organisational theories, and the bureaucratic power play that goes on behind the scenes. The thesis examines three separate reorganisations that occurred in the Australian Army between 1957 and 1965, and the interplay of these four factors in the lead up to each organisational change. In brief, the changes involved the reduction in 1957 of the National Service Training Scheme (based on the Citizen Military Forces), its abandonment in 1960 and its resurrection in 1964 as a means to supplement the Regular Army (ARA). Simultaneously, the Regular Army Field Force was expanded from an under strength brigade to a significant force ready to fight in two or more theatres at one time. Central to the ascendancy of the ARA was the introduction in 1960 and the abandonment in December 1964 of the Australian pentropic organisation, based on the United States' short lived pentomic structure. The changes that occured during this period set the scene for Australia's military involvement in the Vietnam War, and provided a basic organisational structure for the Army's combat elements that remains today essentially the same as it was in 1965.