John McDiarmid was born and lived in Ballarat West. He enlisted on 17th August 1914, the day that recruiting opened in Ballarat for the Great War. He was 24 years old, single and employed as a labourer. On 3rd November 1915 he marched into the Transport Section of the 8th Infantry Battalion from Middle East Expeditionary Force Base Camp at Maadi, Egypt. Later, on 7th January he moved to Serapeum and the 1st Division Train.

He marched into No. 2 Convalescent Depot in preparation for return to Australia because of his health. On 23rd May 1917 he embarked on HMT Ayrshire and arrived in Melbourne on 17th July 1917. After completing the necessary procedures, including a detailed medical check, he was discharged from the AIF on 1st September 1917 because he was medically unfit for military service. His disabilities were identified as shell shock and valvular disease of the heart. Tree No. 36, an elm, was planted in the Ballarat Avenue of Honour, by Miss Winifred Sainsbury, a 'Lucas Girl', on 4th June 1917.