John was born in the Bourke District of NSW, the eldest child of William and Rose Nicholls. By 1898 the family were living in the Inverell District. John was a twenty four year old Stockman when, after passing his medical examination at Inverell, he enlisted at Narrabri in September 1915. He had been a member of the Rocky Dam Rifle Club near Yetman and previously rejected for war service due to his eyesight.
John joined the 18th Battalion, 11th Reinforcement and left Australia on HMAT A71 Nestor in April 1916. After several weeks in England he was sent to France in September. The following month he was wounded in action and eventually transferred to England where he was admitted to 4th London General Hospital for treatment of a shrapnel wound to his arm as well as bronchitis.
He returned to France in January 1917. Five months later he was sick and again returned to England and admitted to Colchester Military Hospital before being transferred to other hospitals over the next few weeks. John returned to Australia in June 1918 and was discharged. He also served during World War II.
John Nicholls is likely to be the E. Nicholls recorded on the Yetman Honor Roll. His name is also inscribed on the Inverell Honor Roll.