In December 1915 the 3rd Battalion was evacuated from the Gallipoli peninsula and withdrawn to Egypt again, where it took part in the defence of the Suez Canal before being sent to France to fight on the Western Front in March 1916.

For the next two and a half years the unit would serve in the trenches in France and Belgium and would take part in many of the major battles fought during that time.

In 1942, following the entry of Japan into the war, the 3rd Battalion (The Werriwa Regiment) was mobilised and brought up to its full wartime establishment with national servicemen.

In July the Japanese landed around Gona and as reinforcements were brought up from Australia, elements of the 30th Brigade began a number of delaying actions around Kokoda.

The 3rd Battalion, AIF, was raised soon after the declaration of war, and began concentrating at Randwick, drawing its recruits from the Werriwa area of New South Wales.

[3] After undertaking another period of training in Egypt, the battalion was employed in the defence of the Suez Canal, before being committed to the Gallipoli Campaign.

[3] As a stalemate settled over the peninsula the battalion was involved in the defence of the beachhead, before taking part in the Battle of Lone Pine in August.

It was during this battle, at Sasse's Sap, that Private John Hamilton, performed the deeds that led to him receiving the Victoria Cross.

[3] After the withdrawal from Gallipoli, the battalion returned to Egypt where they were once again used in the defence of the Suez Canal against the Turks and the AIF undertook a period of reorganisation and expansion.

[6] However, due to the large numbers of militiamen that volunteered for service with the AIF many of these units were greatly depleted and it was not until after the war, in 1919, that the compulsory training scheme began again.

[12] In January 1942, following the Japanese attacks on Pearl Harbor and the British in Malaya, the situation in the Pacific worsened and many Australians began to worry about invasion.

[Note 2] The 3rd Battalion was one of these and upon mobilisation it was brought up to its wartime establishment with a number of drafts of national servicemen recruited from regional New South Wales and the Australian Capital Territory.

[8] The battalion began training in earnest near Maitland, New South Wales, before being sent along with the rest of the 14th Brigade to the coast to undertake defensive duties near Newcastle.

[8] Soon after the Japanese, having reached the limit of their supply lines, began to withdraw and the 3rd Battalion subsequently participated in the advance back up the Kokoda Trail, carrying out patrolling operations as they re-occupied numerous villages that had been lost earlier in the campaign.

[3] Late in October, after the Second Battle of Eora Creek – Templeton's Crossing, the battalion was withdrawn from the line for a brief period of rest at Myola, before assuming defensive responsibilities for Kokoda village on 3 November 1942.

[8] Based on the Atherton Tablelands in Queensland, the battalion was brought back up to establishment and the 30th Brigade was transferred to the 6th Division, with a view to participating in further operations in New Guinea.

[8] In 1948, the 3rd Battalion (Werriwa Regiment) was re-raised as part of the Citizens Military Force (CMF), which was the forerunner to the Australian Army Reserve that currently exists.