Born in Geelong, Victoria and a farmer by occupation, Oliver Coates was 30 years and single when enlisted on the 7th of June 1916 in the 39th Battalion, 3rd Reinforcement, Australian Imperial Force, with the rank of Private, Number 2061, and was listed as returned to Australia on the 31st of March 1919. His Unit embarked from Melbourne, Victoria, on board HMAT A9 'Shropshire' on the 25th of September 1916. Admitted to Hospital sick on the 6th of January 1917, ex 3rd ADBD; on the 15th of August 1917 admitted to Eastbourne Military Hospital to Weymouth Gunshot wound right shoulder; on the 1st of October 1918 admitted to hospital sick ex A.I.B.D.; on the 23rd of June 1918 to Hospital sick. On the 25th of January 1919 proceeded to England per 'Golden Eagle' TACHYCARDIA, sick. On the 15th of February 1919 discharged from Hospital Furlo and report No.1 CD (Tachycardiac). Returned to Australia per 'Khyber' on the 31st of March 1919 and disembarked on the 21st of May 1919. Discharged on the 26th of September 1919. Tree No. 2435