Born in Ballart, Grant, Victoria and a Butcher by trade, William Isaac Cook was 25 years and married when enlisted on the 14th of July 1915 in the 31st Battalion, C Company, Australian Imperial Force, with the rank of Private, Number 617. His Unit embarked from Melbourne, Victoria, on board HMAT A62 'Wandilla' on the 9th of November 1915. Admitted to Hospital sick on the 26th of March 1916. Promoted Corporal to complete establishment in the Field on the 1st of September 1916, France; admitted to Hospital – fractured ankle, accidental – France on the 5th of October 1916. Embarked on H.S. 'Panama' for England ex Havre- fractured ankle, accidental on the 19th of October 1916. Disembarked on the 13th of February 1917 and Discharged on the 17th of May 1917. Tree No. 1168