John Henry Llewellyn Turnbull was born in 1883 at Caramut, Victoria. He was working as an engine driver at Geelong when he enlisted with the Australian Imperial Force (AIF) on 11 November 1914. The 31-year-old was allotted the service number 1433 and the rank of private and was assigned to the 8th Infantry Battalion. Turnbull embarked from Melbourne on 2 February 1915 aboard the troopship HMAT Clan McGillivray.

Turnbull took part in the landing at Gallipoli on 25 April 1915 and wrote in his diaries of the chaos of that day, including the boats half full of wounded before they even reached the shore. In August he was evacuated to Egypt with dysentery but returned to Gallipoli in November to re-join the 8th Battalion. After the evacuation from Gallipoli, he was transferred between units several times. In May 1916, he was transferred for the final time to the 5th Divisional Ammunition Column as a driver. Arriving in France in June 1916, he served with the column on the Western Front for the remainder of the war, often detailing in his diaries the trials and tribulations of driving donkeys and their carts through the incessant mud and cold.

Turnbull returned to Australia on 29 January 1919 and was discharged on 30 March 1919. John Henry Llewellyn Turnbull died at Heidelberg, Victoria at the age of 71 in 1954.