Per his military service record, John McNamara was born at Sydney, N.S.W. His WWI service record shows that he initially tried to enlist on 14th December 1914 at Traralgon in Victoria, where he gave his age as 47 years. (Based on his age given in his entry in the Sudan Nominal Roll on the Australian War Memorial website, it is likely he was even older). On his enlistment papers when he joined the Coo-ees at Gilgandra, he miraculously lost two years, giving his age as 45 years and 2 months. He listed his marital status as single, and his occupation as a butcher. His description on his medical was height 5 feet 11 inches tall, weight 160 ½ lbs., with a medium complexion, grey eyes, and light brown hair. His religious denomination was Roman Catholic. He completed his medical on the 9th October 1915 at Gilgandra, and was attested by Captain Nicholas on the 9th October 1915 at Gilgandra. He claimed to have 5 years in the Regular Forces of New South Wales throughout the Boer War, and a total of 15 years’ previous military service. He gave his address as c/- H. Burns, Exhibition Dairy, Botany Road, Sydney. He listed his next of kin as his nephew, Valentine McNamara, Exhibition Dairy, Botany Road, Sydney.
After completing the march he went to Liverpool Camp as reinforcement for the 13th Battalion.
After two periods of being absent without leave (17th to 24th January 1916, and 3rd to 11th February 1916), on the 16th February 1916 Private McNamara was discharged with his services no longer being required.