The corps initially participated in the defence of the Suez Canal before being transferred to the Western Front in France and Belgium in late March 1916.

[2] The corps' divisions were initially manning the defences east of the Suez Canal against the anticipated Turkish invasion of Egypt.

[4][5] In France the I ANZAC Corps was attached to the British Second Army, and initially positioned in a relatively quiet sector south of Ypres in order to gain experience of trench warfare.

[6] On 5 May I ANZAC experienced its first combat on the Western Front when the Germans launched a raid on the 20th Battalion's positions following an artillery barrage, resulting in 100 casualties, and some men and equipment being captured.

[7] In mid-July 1916, with the Somme Offensive faltering, the British commander-in-chief, General Douglas Haig, required fresh divisions to continue the advance.

[9] Pozières had been attacked unsuccessfully four times prior, however on 23 July 1916 the 1st Division managed to capture the village after making an advance of 1,000 yards.

[12] 1st Division's assault had been successful largely because of good staff work and preparation, however, the divisional commander, Major General Harold Walker, had also refused to be pressured by Gough into attacking before he was ready.

The 2nd Division's commander, Major General James Gordon Legge, however, did not and in the end he ordered an attack on 29 July without having carried out adequate planning.

[11] As a result of these losses, the corps was withdrawn to a quiet sector during September and October 1916, before returning to the Somme in November.

[14] Throughout the end of 1916 and the beginning of 1917, I ANZAC was confined to defensive duties, however, in the spring they began a series of patrols along the front, during which it was discovered that the Germans were withdrawing to the Hindenburg Line.

[21][22] While the composition of I ANZAC Corps changed a number of times[9][15][Note 2] with divisions being attached and detached as required for involvement in a particular campaign, the following order of battle is included for illustrative purposes.