 Complete the following phrase:  Following the lead of the US Army, in 1960 the Australian Army had replaced its former triangular divisional structure of three infantry battalions under a brigade headquarters, with a pentropic organisation consisting of five larger battalions without a brigade layer between division and battalion headquarters. This had the effect of reducing the total number of Australian battalions, while increasing their individual strength. Wilton was unhappy with the pentropic structure, reasoning that the number of battalions, rather than their relative strength, was the overriding factor when considering potential overseas deployments. The US had in any event abandoned the system in June 1961. In October 1964, Wilton commissioned a review that ultimately recommended a return to the triangular formation. In the meantime, as a response to the 