In 1916, when working for the Union Steamship Company, he volunteered for the Māori Reinforcements and became one of 500 Cook Islanders who joined the New Zealand Expeditionary Force. He was initially stationed with the New Zealand Rarotongan Company in El Qantara, Egypt, and in early 1917 was promoted to Sergeant. In late 1917 he participated in the Battle of Jerusalem, and in February 1918 he was awarded the Distinguished Conduct Medal "for conspicuous gallantry and devotion to duty while in command of a platoon". He was the only Pacific islander in the NZEF to receive this decoration