Claude William Mills was the only son of William Bothwell Mills and Emily Jane Mills, nee Bienvenu. He hasd two sisters, May Louise Mills, born in 1883, died 1894 and Isabella May Dimond Mills, born in 1897 and died 1992. Claude Mills born on 4 November, 1892 in South Yarra and enlisted to fight when he was 22 years and 3 months old, on 18 February, 1915. He was then single, with his next of kin his father, living at 12 The Grange Malvern. Following his parents' death, William Mills in 1933 and his wife Emily in 1937, Claude Mills would inherit the house and live in it for his lifetime. In 1915, he identified himself as a clerk, with 2 years State School Cadet Training. He was 5' 7", with grey eyes and dark brown hair and belonged to the Presbyterian Church. His Embarkation Roll would mistakenly identify him as living in East Melbourne, but this is a mistake, mixing East Malvern with East Melbourne on the form.

He was immediately placed with the 6th Field Ambulance and, on 4 July 1915,  embarked for the war on board H.M.A.T. Ajana A31. The dates suggest he was involved in the Gallipoli Campaign, but probably as a clerk rather than an ambulance orderly. Each Field Ambulance Unit had special responsibilities for one of the Army Brigades. The Field Ambulance was responsible for setting up the chain of casualty evacuation units taking wounded soldiers away from the battlefront: Regimental Aid Posts were immediately behind the line; 600 yards behind them were the Bearer Relay Posts, taking casualties rearward to an Advanced Dressing Station (ADS). The Field Brigade also operated a 'walking wounded' Collecting Station, as well as rest rooms and local sick rooms. Each Field Ambulance Brigade would establish at least one one ADS and one MDS (Main Dressing Station).

Claude Mills was with the 6th Field Ambulance until 9 April, 1917, when he was promoted to Corporal and transferred to the 2nd Division Headquarters. On 9 July, 1917, he was again promoted to Segeant. He was with the 2nd Div H/Q until after the end of the war, finally returning to Australia on H.M.A.T. Warwickshire on 28 May 1919.

In the late 1920s, he was living in East Malvern at his parents' house and working as a clerk. He married in 1940 to Isabella Marie Dimond. They do not appear to have had any children.  In 1958, probably following his retirement - he was 66 at the time - he and Isabella spent 6 months in England, before returning to Australia.

Claude William Mills died on 28 November, 1976.