Anticipating the entry of the Japanese Empire into the Second World War, in September 1940 the New Zealand Military Forces raised the 8th Infantry Brigade Group for garrison duty in Fiji.

[5][Note 1] Some others, including Voelcker who had been promoted to lieutenant colonel, remained in Fiji to form the cadre around which the battalion was to be reformed with newly arrived personnel.

Many personnel had only received minimal military training in New Zealand before being shipped to Fiji and much time had to be spent on the basics of warfare and tactics.

[6] Towards the end of 1941 the likelihood of hostilities commencing in the Pacific increased, so the battalion began work on defence emplacements in their sector along the coast.

[6] Coincidentally manning their defence emplacements on a training exercise when news of the Japanese attack on Pearl Harbor reached Fiji, extra supplies of ammunition were immediately handed out and the battalion remained on action stations for three days before being stood down.

[9][Note 2] The 34th Battalion continued performing garrison duties and carrying out training exercises until, with the United States now taking responsibility for the defence of Fiji, it was relieved by American forces in July 1942.

To be formed in New Zealand, the division was based around the recently returned 8th and 14th Brigades, and the battalions making up these formations, and commanded by Major General Harold Barrowclough.

[12] Barrowclough set about organising the new division and implemented training programs to prepare his new command for fighting against the Japanese in the Pacific.

[13] However, at the request of Vice Admiral Robert L. Ghormley, commander of the South Pacific Area, the 34th Battalion was selected in October 1942 to garrison Tonga.

[20] However along the way, the troops stopped briefly at Port Vila in the New Hebrides to carry practice amphibious operations with landing craft before continuing onto Guadalcanal.

This was a small battle group, which also included a section of machine gun troops, to provide security for American construction and technical personnel that would be landed at Soanotalu, on the north coast of Mono Island, to establish a radar station.

[28] On Mono Island, the main landing along the south coast had been achieved with relative ease, with few casualties although they had to fend off some attacks that night.

A small group of six soldiers from 34th Battalion plus three Americans held a blockhouse throughout the night and by dawn, over 50 Japanese had been killed for the loss of five men.

By this stage, the battalion was commanded by Lieutenant Colonel J. Reidy, taking over from Eyre who was now too old for active service and had returned to New Zealand.

However, by the time those soldiers returning from furlough had assembled at Papakura Military Camp, it had been officially announced that the 3rd Division was to be disbanded and the 34th Battalion ceased to exist on 20 October 1944.