Enlisted 1 July 1916 on Rarotonga and disembarked from SS Malwa at Suez 27 December 1916. Posted to the Rarotongan Company 7 April 1917 and detached to the 10th Heavy Battery, Royal Artillery from 5 October 1917 to 9 November 1917. Admitted to the 27th General Hospital, Abbassia on 26 November 1917 with pyrexia and was transferred to the 44th Stationary Hospital, Kantara 24 November 1917 and to the Aotea Convalescent Home from the 28 November to 6 December 1917. Rejoined the Rarotongan Company and was admitted to the 129th Field Ambulance with measles 14 August 1918 until 29 August 1918. Embarked for New Zealand on SS Malta 14 of December 1918 and discharged 20 March 1919.

The Cook Islands Roll of Honour board at the RSA Nikao Rarotonga records his name as 'K. Ivitu'.

While there is no official record in his military documents that he was promoted from Private to Lance Corporal, his discharge certificate states a rank of Lance Corporal