John Harold Davis was born on 27 July 1883 in Bathurst, New South Wales, to Elizabeth (née Moore) and John Davis. Following his schooling, Davis worked as a labourer and, in 1912, immigrated to Canada and gained work as a bridgeman.
Following the outbreak of the First World War, Davis joined the Canadian Militia on 14 August 1914 and was posted to the 101st Regiment. Six weeks later, in order to embark on service overseas, he enlisted in the Canadian Expeditionary Force in Valcartier, Quebec. On his attestation paper, dated 22 September 1914, he recorded 1880 as his year of birth—increasing his age by three years—but accurately gave Bathurst as his place of birth. He also recorded his mother, then living in Millthorpe, New South Wales, as his next of kin.
Allocated the service number 18790, Davis was posted to the 9th Battalion as a private. On 4 October 1914, he embarked aboard SS Zealand at Quebec and sailed for the United Kingdom. He spent some time at Tidworth Camp, undergoing training on the Salisbury Plain. Slated for transfer to B Company of the 1st Battalion (Western Ontario Regiment), Davis spent some time with the Canadian Infantry Base Depot at Tidworth before embarking for France on 12 April 1915 as part of the reinforcements to the 1st Battalion. He joined his battalion in Rouen a fortnight later.
Davis' battalion was subsequently moved north into Belgium. On 24 December 1915, while passing through the village of Wulverghem on duty as a messenger, Davis was killed by a German artillery shell. He is buried in St Quentin Cabaret Military Cemetery in Heuvelland, Belgium.
Davis' parents were issued with a Memorial Cross and a Memorial Plaque and Scroll in recognition of their son's service and sacrifice. He is commemorated in the Australian War Memorial's Commemorative Roll, the Canadian First World War Book of Remembrance, and on the Commonwealth War Graves Commission's Debt of Honour Register.