He was awarded the Distinguished Service Order, the citation reading: ""For gallantry and devotion to duty in connection with the operations at the Dardanelles (Mediterranean Expeditionary Force). On the night of 2–3 May 1915 during the operations in the neighbourhood of Gape Tepe for gallantry and resource in rallying his men, and leading them forward at critical moments"." Later in the campaign Waite served as the adjutant of the New Zealand Engineers and was twice mentioned in dispatches. Evacuated to England with dysentery, he was repatriated to New Zealand in 1916. His service with the NZEF ceased and he returned to the TF in his pre-war rank of major. He took up an appointment as Chief Engineer Instructor of the NZEF training camps. Shortly before the end of the war, Waite wrote a brief account of New Zealand's contributions to the Gallipoli Campaign. Authorities invited him to prepare a more substantial work and this resulted in "The New Zealanders at Gallipoli", the first volume in a series of the "Official History of New Zealand's Effort in the Great War", published in 1919. Two years later it was republished as a revised edition. Waite also worked on the production of the three other volumes in the series, which were published around the same time. After the war, Waite returned to his Balclutha property which he converted to dairy farming. He remained a member of the TF for several years and was a major in the Otago Mounted Rifles Regiment before being promoted to lieutenant colonel and becoming its commander from 1927 to 1930. For his prolonged service with the TF, he eventually received the Colonial Auxiliary Forces Officers' Decoration. In 1935 he was awarded the King George V Silver Jubilee Medal. Already involved in the dairying industry, he began to participate in the governance of the sector and set up the Co-Operative Dairy Company of Otago. He later joined the New Zealand Farmer's Union and was president of its Otago Branch. As well as his work in the dairying sector, Waite soon became involved in local politics and joined the Reform Party. He first stood for election to the House of Representatives in , when he defeated the incumbent in the electorate, John Edie of the Liberal Party, with ease. He was one of 13 new members in a House of 80 representatives. In the , he was challenged by Joseph Stephens, who was an independent candidate describing himself as Liberal–Labour.