Pentropic division

The Pentropic organisation was a military organisation used by the Australian Army between 1960 and 1965. It was based on the United States Army's pentomic organisation and involved reorganising most of the Army's combat units into units based on five elements, rather than the previous three or four sub-elements. The organisation proved unsuccessful, and the Army reverted to its previous unit structures in early 1965.

The decision to adopt the Pentropic organisation was driven by a desire to modernise the Army and ensure that Australian units were able to integrate with those of the United States Army. While the US Pentomic organisation had been implemented in 1957 to improve the Army's ability to operate during a nuclear war, the Australian organisation was optimised for limited wars in South East Asia in which there was a chance that nuclear weapons might be used. Both structures were designed to facilitate independent operations by the sub-units of divisions. The Australian Pentropic division was intended to be air portable, capable of fighting in a limited war and capable of conducting anti-guerrilla operations.

The key element of the Pentropic organisation was the reorganisation of divisions into five combined arms battle groups. These battle groups consisted of an infantry battalion, field artillery regiment, engineer field squadron and other combat and logistic elements, including armoured, aviation and armoured personnel carrier units as required. These battle groups would be commanded by the commanding officer of their infantry battalion and report directly to the headquarters of the division as brigade headquarters were abolished as part of the reorganisation.

When the Pentropic organisation was implemented in 1960 the Australian Army was reorganised from three divisions organised on what was called the Tropical establishment (the 1st, 2nd and 3rd divisions) into two Pentropic divisions (the 1st and 3rd). While two of the Army's three regular infantry battalions were expanded into the new large Pentropic battalions, the 30 reserve Citizens Military Force (CMF) battalions were merged into just nine battalions. This excluded the University Regiments and the Papua New Guinea Volunteer Rifles which remained unchanged. There was a similar effect on the other CMF units, with most being merged into new, larger units. The other regular infantry battalion remained on the previous tropical establishment as it formed part of the 28th Commonwealth Brigade in Malaysia. As part of this reorganisation the Army replaced its outdated weapons with more modern weapons, most of which were supplied from the United States. It was believed that these new weapons would further improve the Army's combat power and the ability of sub-units to operate independently.

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