First Australian Imperial Force

The First Australian Imperial Force was the main expeditionary force of the Australian Army during the First World War. It was formed as the Australian Imperial Force on 15 August 1914 following Britain's declaration of war on Germany, with an initial strength of one infantry division and one light horse brigade. The infantry division subsequently fought at Gallipoli between April and December 1915, with a newly raised second division, as well as three light horse brigades, reinforcing the committed units.
After being evacuated to Egypt, the AIF was expanded to five infantry divisions, which were committed to the fighting in France and Belgium along the Western Front in March 1916. A sixth infantry division was partially raised in 1917 in the United Kingdom, but was broken up and used as reinforcements following heavy casualties on the Western Front. Meanwhile, two mounted divisions remained in the Middle East to fight against Turkish forces in the Sinai and Palestine. The AIF included the Australian Flying Corps, the predecessor to the Royal Australian Air Force, which consisted of four combat and four training squadrons that were deployed to the United Kingdom, the Western Front and the Middle East throughout the war.
An all volunteer force, by the end of the war the AIF had gained a reputation as being a well-trained and highly effective military force, playing a significant role in the final Allied victory. However, this reputation came at a heavy cost with a casualty rate among the highest of any belligerent for the war. The remaining troops were repatriated until the disbandment of the 1st AIF between 1919 and 1921. After the war, the achievements of the AIF and its soldiers, known colloquially as "Diggers", became central to the national mythology of the "Anzac legend". Generally known at the time as the AIF, it is today referred to as the 1st AIF to distinguish it from the Second Australian Imperial Force raised during World War II.

Formation

At the start of the war, Australia's military forces were focused upon the part-time Militia. The small number of regular personnel were mostly artillerymen or engineers, and were generally assigned to the task of coastal defence. Due to the provisions of the Defence Act 1903, which precluded sending conscripts overseas, upon the outbreak of war it was realised that a totally separate, all volunteer force would need to be raised. The Australian government pledged to supply 20,000 men organised as one infantry division and one light horse brigade plus supporting units, for service "wherever the British desired", in keeping with pre-war Imperial defence planning. The Australian Imperial Force subsequently began forming shortly after the outbreak of war and was the brain child of Brigadier General William Throsby Bridges and his chief of staff, Major Brudenell White. Officially coming into being on 15 August 1914, the word 'imperial' was chosen to reflect the duty of Australians to both nation and empire. The AIF was initially intended for service in Europe. Meanwhile, a separate 2,000-man force—known as the Australian Naval and Military Expeditionary Force —was formed for the task of capturing German New Guinea. In addition, small military forces were maintained in Australia to defend the country from attack.
Upon formation, the AIF consisted of only one infantry division, the 1st Division, and the 1st Light Horse Brigade. The 1st Division was made up of the 1st Infantry Brigade under Colonel Henry MacLaurin, an Australian-born officer with previous part-time military service; the 2nd, under Colonel James Whiteside McCay, an Irish-born Australian politician and former Minister for Defence; and the 3rd, under Colonel Ewen Sinclair-Maclagan, a British regular officer seconded to the Australian Army before the war. The 1st Light Horse Brigade was commanded by Colonel Harry Chauvel, an Australian regular, while the divisional artillery was commanded by Colonel Talbot Hobbs. The initial response for recruits was so good that in September 1914 the decision was made to raise the 4th Infantry Brigade and 2nd and 3rd Light Horse Brigades. The 4th Infantry Brigade was commanded by Colonel John Monash, a prominent Melbourne civil engineer and businessman. The AIF continued to grow through the war, eventually numbering five infantry divisions, two mounted divisions and a mixture of other units. As the AIF operated within the British war effort, its units were generally organised along the same lines as comparable British Army formations. However, there were often small differences between the structures of British and Australian units, especially in regards to the AIF infantry divisions' support units.
Hastily deployed, the first contingent of the AIF was essentially untrained and suffered from widespread equipment shortages. In early 1915 the AIF was largely an inexperienced force, with only a small percentage of its members having previous combat experience. However, many officers and non-commissioned personnel had previously served in the pre-war permanent or part-time forces, and a significant proportion of the enlisted personnel had received some basic military instruction as part of Australia's compulsory training scheme. Predominantly a fighting force based on infantry battalions and light horse regiments—the high proportion of close combat troops to support personnel was exceeded only by the New Zealand Expeditionary Force —this fact at least partially accounted for the high percentage of casualties it later sustained. Nevertheless, the AIF eventually included a large number of logistics and administrative units which were capable of meeting most of the force's needs, and in some circumstances provided support to nearby allied units. However, the AIF mainly relied on the British Army for medium and heavy artillery support and other weapons systems necessary for combined arms warfare that were developed later in the war, including aircraft and tanks.

Organisation

Command

When originally formed in 1914 the AIF was commanded by Bridges, who also commanded the 1st Division. After Bridges' death at Gallipoli in May 1915, the Australian government appointed Major General James Gordon Legge, a Boer War veteran, to replace Bridges in command of both. However, British Lieutenant General Sir John Maxwell, the commander of British Troops in Egypt, objected to Legge bypassing him and communicating directly with Australia. The Australian government failed to support Legge, who thereafter deferred to Lieutenant General William Birdwood, the commander of the Australian and New Zealand Army Corps. When Legge was sent to Egypt to command the 2nd Division, Birdwood made representations to the Australian government that Legge could not act as commander of the AIF, and that the Australian government should transfer Bridges' authority to him. This was done on a temporary basis on 18 September 1915. Promoted to major general, Chauvel took over command of the 1st Division in November when Major General Harold Walker was wounded, becoming the first Australian-born officer to command a division. When Birdwood became commander of the Dardanelles Army, command of the Australian and New Zealand Army Corps and the AIF passed to another British officer, Lieutenant General Alexander Godley, the commander of the NZEF, but Birdwood resumed command of the AIF when he assumed command of II ANZAC Corps upon its formation in Egypt in early 1916. I ANZAC Corps and II ANZAC Corps swapped designations on 28 March 1916. During early 1916 the Australian and, to a lesser extent, New Zealand governments sought the establishment of an Australian and New Zealand Army led by Birdwood which would have included all of the AIF's infantry divisions and the New Zealand Division. However, General Douglas Haig, the commander of the British Empire forces in France, rejected this proposal on the grounds that the size of these forces was too small to justify grouping them in a field army.
Birdwood was officially confirmed as commander of the AIF on 14 September 1916, backdated to 18 September 1915, while also commanding I ANZAC Corps on the Western Front. He retained overall responsibility for the AIF units in the Middle East, but in practice this fell to Godley, and after II ANZAC Corps left Egypt as well, to Chauvel who also commanded the ANZAC Mounted Division. Later promoted to lieutenant general, he subsequently commanded the Desert Mounted Corps of the Egyptian Expeditionary Force; the first Australian to command a corps. Birdwood was later given command of the Australian Corps on its formation in November 1917. Another Australian, Monash, by then a lieutenant general, took over command of the corps on 31 May 1918. Despite being promoted to command the British Fifth Army, Birdwood retained command of the AIF. By this time four of the five divisional commanders were Australian officers. The exception was Major General Ewen Sinclair-Maclagan, the commander of the 4th Division, who was a British Army officer seconded to the Australian Army before the war, and who had joined the AIF in Australia in August 1914. The vast majority of brigade commands were also held by Australian officers. A number of British staff officers were attached to the headquarters of the Australian Corps, and its predecessors, due to a shortage of suitably trained Australian officers.

Structure

Infantry divisions

The organisation of the AIF closely followed the British Army divisional structure, and remained relatively unchanged throughout the war. During the war, the following infantry divisions were raised as part of the AIF:

Each division comprised three infantry brigades, and each brigade contained four battalions. Australian battalions initially included eight rifle companies; however, this was reduced to four expanded companies in January 1915 to conform with the organisation of British infantry battalions. A battalion contained about 1,000 men. Although the divisional structure evolved over the course of the war, each formation also included a range of combat support and service units, including artillery, machine-gun, mortar, engineer, pioneer, signals, logistic, medical, veterinary and administrative units. By 1918 each brigade also included a light trench mortar battery, while each division included a pioneer battalion, a machine-gun battalion, two field artillery brigades, a divisional trench mortar brigade, four companies of engineers, a divisional signals company, a divisional train consisting of four service corps companies, a salvage company, three field ambulances, a sanitary section and a mobile veterinary section. These changes were reflective of wider organisational adaption, tactical innovation, and the adoption of new weapons and technology that occurred throughout the British Expeditionary Force.
At the start of the Gallipoli Campaign, the AIF had four infantry brigades with the first three making up the 1st Division. The 4th Brigade was joined with the sole New Zealand infantry brigade to form the New Zealand and Australian Division. The 2nd Division had been formed in Egypt in 1915 and was sent to Gallipoli in August to reinforce the 1st Division, doing so without its artillery and having only partially completed its training. After Gallipoli, the infantry underwent a major expansion. The 3rd Division was formed in Australia and completed its training in the UK before moving to France. The New Zealand and Australian Division was broken up with the New Zealand elements forming the New Zealand Division, while the original Australian infantry brigades were split in half to create 16 new battalions to form another four brigades. These new brigades were used to form the 4th and 5th Divisions. This ensured the battalions of the two new divisions had a core of experienced soldiers. The 6th Division commenced forming in England in February 1917, but was never deployed to France and was broken up in September of that year to provide reinforcements to the other five divisions.
The Australian infantry did not have regiments in the British sense, only battalions identified by ordinal number. Each battalion originated from a geographical region, with men recruited from that area. New South Wales and Victoria, the most populous states, filled their own battalions while the "Outer States"—Queensland, South Australia, Western Australia and Tasmania—often combined to assemble a battalion. These regional associations remained throughout the war and each battalion developed its own strong regimental identity. The pioneer battalions were also mostly recruited regionally; however, the machine-gun battalions were made up of personnel from all states.
During the manpower crisis following the Third Battle of Ypres, in which the five divisions sustained 38,000 casualties, there were plans to follow the British reorganisation and reduce all brigades from four battalions to three. In the British regimental system this was traumatic enough; however, the regimental identity survived the disbanding of a single battalion. In the Australian system, disbanding a battalion meant the extinction of the unit. In September 1918, the decision to disband seven battalions—the 19th, 21st, 25th, 37th, 42nd, 54th and 60th—led to a series of "mutinies over disbandment" where the ranks refused to report to their new battalions. In the AIF, mutiny was one of two charges that carried the death penalty, the other being desertion to the enemy. Instead of being charged with mutiny, the instigators were charged as being absent without leave and the doomed battalions were eventually permitted to remain together for the forthcoming battle, following which the survivors voluntarily disbanded. These mutinies were motivated mainly by the soldiers' loyalty to their battalions.
The artillery underwent a significant expansion during the war. When the 1st Division embarked in November 1914 it did so with its 18-pounder field guns, but Australia had not been able to provide the division with the howitzer batteries or the heavy guns that would otherwise have been included on its establishment, due to a lack of equipment. These shortages were unable to be rectified prior to the landing at Gallipoli where the howitzers would have provided the plunging and high-angled fire that was required due to the rough terrain at Anzac Cove. When the 2nd Division was formed in July 1915 it did so without its complement of artillery. Meanwhile, in December 1915 when the government offered to form another division it did so on the basis that its artillery would be provided by Britain. In time though these shortfalls were overcome, with the Australian field artillery expanding from just three field brigades in 1914 to twenty at the end of 1917. The majority of the heavy artillery units supporting the Australian divisions were British, although two Australian heavy batteries were raised from the regular Australian Garrison Artillery. These were the 54th Siege Battery, which was equipped with 8-inch howitzers, and the 55th with 9.2-inch howitzers.