Having already despatched the original Australian Imperial Force and seen them go into action at Gallipoli, three more brigades were formed and sailed for Egypt in May and June 1915. By August they had been joined there by new artillery units from Australia and other ancillary units largely improvised from the reserves in Egypt. They were formed into the 2nd Austraian Division. In August 1915 the Division reinforced the garrison at Gallipoli. Thereafter the Division fought in many of the major actions of the war, including:

1915
Gallipoli campaign
The Division withdrew from Gallipoli on 19-20 December 1915 and returned to Egypt.

1916
The Division was warned for France and sailed on 13 March 1916. It then remained in France and Flanders for the rest of the war. The Division then took part in the following battles and engagements:
The Battle of Pozieres including the fighting for Mouquet Farm (a phase of the Battles of the Somme 1916)

1917
Operations on the Ancre including the capture of the Thilloys and Irles
During the German retreat to the Hindenburg Line, the Division captured Bapaume
The Arras Offensive, in which the Division fought the German attack on Lagnicourt and in the Battle of Bullecourt
The Battle of the Menin Road**
The Battle of Polygon Wood**
The Battle of Broodseinde**
The Battle of Poelcapelle**
The Second Battle of Passchendaele**
The battles marked ** are phases of the Third Battle of Ypres

1918
The Australian Divisions were not affected by the restructuring of the army to having three brigades per Division, that took place in the British Divisions in February 1918.
The Battle of the Avre (a phase of the First Battles of the Somme 1918)
The Capture of Hamel
The Second Battle of Bapaume in which the Division captured Mont St Quentin ( a phase of the Second Battles of the Somme 1918)
The Battle of the St Quentin Canal++
The Battle of Beaurevoir in which the Division captured Montbrehain++
The battles marked ++ are phases of the Battles of the Hindenburg Line

The Division was not selected to advance into Germany. Demobilisation commenced in early 1919 and by March 1919 the Division merged with 5th Australian Division.

The order of battle of the 2nd Australian Division

5th Australian Brigade
17th Bn, the Australian Infantry
18th Bn, the Australian Infantry
19th Bn, the Australian Infantry
20th Bn, the Australian Infantry
5th Australian Machine Gun Company	formed February 1916 left to move into 2nd Australian MG Battalion February 1918
5th Australian Trench Mortar Battery	formed April 1916
6th Australian Brigade
21st Bn, the Australian Infantry
22nd Bn, the Australian Infantry
23rd Bn, the Australian Infantry
24th Bn, the Australian Infantry
6th Australian Machine Gun Company	formed February 1916 left to move into 2nd Australian MG Battalion February 1918
6th Australian Trench Mortar Battery	formed April 1916
7th Australian Brigade
25th Bn, the Australian Infantry
26th Bn, the Australian Infantry
27th Bn, the Australian Infantry
28th Bn, the Australian Infantry
7th Australian Machine Gun Company	formed February 1916 left to move into 2nd Australian MG Battalion February 1918
7th Australian Trench Mortar Battery	formed April 1916
Divisional Troops	under direct command of Divisional HQ
2nd Australian Pioneer Bn	formed in Egypt in March 1916
22nd Australian Machine Gun Company	joined March 1917 left to move into 2nd Australian MG Battalion February 1918
2nd Australian Machine Gun Battalion	formed February 1918
2nd Australian Divisional Train ASC	formed in Egypt in August 1915, later titled 745, 746, 747 and 848 Companies
2nd Australian Mobile Veterinary Section AVC	formed in Egypt in August 1915
2nd Australian Divisional Employment Company	joined January 1917
Divisional Mounted Troops	under direct command of Divisional HQ
13th Australian Light Horse	joined July 1915, broken up February 1916
2nd Australian Cyclist Company	formed in Egypt, left May 1916
Divisional Artillery
4th Australian Brigade, RFA
5th Australian Brigade, RFA
6th Australian Brigade, RFA
22 Australian (Howitzer) Brigade, RFA	formed in Egypt, absorbed by May 1916
2nd Australian Divisional Ammunition Column
1st Australian Heavy Battery RGA	formed at Gallipoli in November 1915, disbanded in December
V.2.A Heavy Trench Mortar Battery RFA	formed June 1916, left February 1918
X.2.A, Y.2.A and Z.2.A Medium Mortar Batteries RFA	formed June 1916; in February 1918, Z broken up and batteries reorganised to have 6 x 6-inch weapons each
Royal Engineers
5th Australian Field Company	formed in Egypt in July 1915, renumbered 8th and left February 1916
6th Australian Field Company	joined from Australia in February 1916
7th Australian Field Company	joined from Australia in February 1916
2nd Australian Divisional Signals Company
Royal Army Medical Corps
5th Australian Field Ambulance	formed in Egypt in August 1915
6th Australian Field Ambulance	formed in Egypt in August 1915
7th Australian Field Ambulance	formed in Egypt in August 1915