Mary Jane Thomas was born in Happy Valley, Victoria, was single and a Nurse when she enlisted with the Nurses (July 1915 – November 1918) on 15 June 1917 at the age of 47. Her unit embarked from Melbourne, Victoria, on board RMS Somali on 30 June 1917. She was assigned to the Heslop War Hospital where she treated wounded soldiers until her transfer to Australia on 5 August 1918.