Born in Richmond, Victoria and a Medical practitioner by trade, William Winn Chaplin was 42 years and married when enlisted on the 7th of August 1915 in the Field Ambulance 10, Australian Imperial Force, with the rank of Captain. His Unit embarked from Melbourne, Victoria, on board HMAT A54 'Runic' on the 20th of June 1916. Appointed Captain in the AMC on the 7th of August 1915 and appointed Captain in A.I.F. on the 1st of March 1916. Promoted Major on the 27th of April 1917. Taken on strength of 3rd Australian General Hospital from 9th Field Ambulance. Embarked return to Australia per 'Margha' on the 5th of March 1919 and disembarked on the 14th of May 1919. Discharged on the 11th of September 1919 with the termination of period of enlistment. Tree No. 1873