In 1917, again in need of reinforcements, Paraire Tomoana composed an additional verse to the song, specifically encouraging enlistment in Ngāti Kahungunu, and other eastern regions of the North Island.

After their initial enlistment, recruits were organised into their respective companies and undertook basic training at Narrow Neck camp in Auckland.

The 1st Māori Contingent departed New Zealand in February 1915 aboard the troop ship Warrimoo, arriving in March for further training in Egypt.

Despite requests made to Major-General Alexander Godley by New Zealand Minister of Defence James Allen and Māori MPs Āpirana Ngata and Maui Pomare, the battalion was not deployed to Gallipoli with the first invasion force in April 1915.

After Gallipoli there was considerable criticism of three officers of the Māori Pioneers, who were charged with desertion in the face of the enemy, despite strong evidence to the contrary.

However, after a short time the unit was reunited and served the rest of the war as pioneers digging trenches and drains, doing farm work, laying railway lines, erecting wire entanglements, burying artillery cables and building a cinema called "Kapai Theatre".

During the winter months of 1916 the pioneers were well behind the front lines in comfortable billets where they were able to use local cafes and hotels, and socialise with French civilians.

In late August 1916 the battalion was engaged at the Somme, and began work on creating the communication trench which became known as Turk Lane.

[9] In 1917 the remnants of the Otago Mounted Rifles Regiment, which made up 50 per cent of the battalion's remaining strength, was replaced by newly arrived Māori reinforcements.

At the conclusion of the war the battalion was involved in an unpleasant incident when a group of Māori soldiers, possibly suffering from battle fatigue, started shooting in a rest camp.

[citation needed] After the war, the Pioneer Battalion was the only unit of the New Zealand Expeditionary Force to return home as a formed body.