John was the son of William and Sarah Day. His birth was registered at Hillgrove NSW in 1894.
He enlisted several times, the last time being in November 1916 under the assumed name of William Anderson. He gave his age as twenty one and address as Gunnedah NSW. Just prior to this he had been in Inverell where he obtained a doctor’s letter stating he had pneumonia and was not fit for service.
John joined the 33rd Battalion, 6 Reinforcement and left Australia on the ship HMAT A72 Beltana on 25 November 1916. After arriving in England in January 1917, it was six months before he was sent to France. By 1919 he was again suffering from pneumonia and subsequently died at a Casualty Clearing Station on 12 March 1919. Private John Day was buried at Charleroi Communal Cemetery, Belgium. His personal effects, including wallet, watch and photos were returned to his father.