Grouped according to calibre, all guns and howitzers of 4½-inch bore or less were strictly considered as Field Artillery which, although administered by the Divisions, was almost invariably fought under the direct orders of the Corps Commander. All guns and howitzers of greater bore, up to the giant 15-inch, were known as Heavy and Siege Artillery.
Regarded from the point of view of mobility, all field guns and that wonderfully useful weapon, the 60-pounder, were horse-drawn, the larger ordnance were tractor-drawn, and the very largest were mounted on railway trains and hauled by steam locomotive.
Finally, as regards tactical utilization, some natures of ordnance were invariably employed for barrage or harassing fire, others for bombardment, others for counter-battery fighting, and yet others for anti-aircraft purposes.
The total ordnance under the orders of the Australian Army Corps naturally fluctuated according to the daily battle requirements, but amounted at times, during the period of the war under consideration, to as many as 1,200 guns of all natures and calibres, grouped in Brigades each of four to six Batteries, each of four to six guns.
This very formidable Artillery equipment far transcended in quantity and dynamic power anything that had been envisaged in the previous years of the war, or in any previous war, as possible of administrative or tactical control under a single Commander. It undoubtedly became a paramount factor in the victories which the Corps achieved. The Artillery of the Corps is entitled to the proud boast that it earned the confidence and gratitude of the Infantry.
It must be left to the imagination to conceive the complexity of the task of keeping this enormous mass of Artillery regularly supplied with its ammunition, of multifarious types and in adequate quantities of each, of allocating to each Brigade and even to each Battery its appropriate task in the general plan, and of advancing the whole organization over half-ruined roads and broken bridges, in order to keep up with the Infantry as the battle moved forward from day to day. It would defy a detailed description intelligible to any but gunnery experts.
The Air Force had, by the summer of 1918, also achieved a great development. The numerous Air Squadrons had embarked upon a policy of specialization in tactical employment, in accordance with the build and capacities of the aeroplanes with which they were equipped. Thus gradually the whole range of utilization became covered, from the small fast single-seater fighting scout, intended to engage and drive off enemy 'planes, to the slower two-seater reconnaissance machines, employed chiefly for photography and for the direction of Artillery fire, and the giant long-distance bombing machines.
The Australian Corps had at its exclusive disposal at all times the No. 3 Squadron of the Australian Flying Corps, and employed the machines for reconnaissance prior to and after battle, and for contact and counter-attack work and Artillery observation during battle. But, whenever the scope of the operations rendered it necessary, the resources of the Corps in aircraft were enormously increased, and as many as a dozen squadrons were on occasions employed, during battle, in low flying pursuit of enemy infantry and transport, in production of smoke screens, in bombing, in ammunition carrying, and in dispatch bearing—over and above usual reconnaissance work designed to keep Corps and Divisional Headquarters rapidly and minutely informed, from moment to moment, of the situation of the Infantry in actual contact with the enemy.
Another branch of the Air Force activities under the direct control of the Corps was the Captive Balloon Service. Some five large captive or kite balloons, carrying trained Artillery Observers, regularly ascended along the Corps front whenever the weather and the conditions of visibility permitted, to a height of from 2,000 to 3,000 feet, and with the aid of powerful telescopes and of telephone wires woven into the anchoring cables, kept the Artillery regularly notified of all visible enemy movement, and of the occurrence of all suitable targets of opportunity, such as the flashes from enemy guns in action.