Born in Wellington, Powles volunteered for the Fourth Contingent to fight in the Second Boer War, serving in Africa from April 1900 to June 1901.

[1][2] Powles volunteered to join the Fourth Contingent raised for service in the Boer South African Republic.

As a non-commissioned officer, he and the rest of the contingent, nicknamed the "Rough Riders", left New Zealand in March 1900 and landed in Portuguese East Africa the following month.

Aside from a brief action at Ottoshoop in August, the Rough Riders spent the majority of their war service in the Transvaal, carrying out reconnaissance patrols and pursuing Boer commandos.

As part of the effort to deprive the Boers of resources, they also helped to destroy crops and round up civilians and cattle, during which they occasionally skirmished with armed commandos.

[6] However, in early April 1915, military planners in London decided that the NZEF would be part of the Allied forces that would open up a new front in the Middle East, by landing on the Gallipoli Peninsula.

[8] Powles would serve throughout the campaign at Gallipoli and in its final stages was commander of the Canterbury Mounted Rifles Regiment.

[1][9] In early 1916, as part of the reorganisation of the NZEF that followed the Allied evacuation from Gallipoli, the Australian and New Zealand Mounted Division was formed with Powles, promoted to acting lieutenant colonel, appointed assistant adjutant and quartermaster general.

[1][4] This was based on a draft originally prepared by Major A. H. Wilkie, another veteran of the fighting in the Middle East, and was published in 1922 as The New Zealanders in Sinai and Palestine.

[12] During the Second World War he was recalled to duty and served as the commandant of Waiouru Military Camp from 1941 until the cessation of hostilities.