Benjamin was born in Wolverhampton in 1894, the son of Arthur Oliver and Sarah Ann Doley. In 1901 they were living at 82 Newhampton Road West, Wolverhampton, together with Benjamin’s sisters, Violet and Daisy, brothers Samuel and Charles, and uncle Thomas. By 1911 they had moved to 106 Owen Road, and Benjamin had become a house painter. He also had an additional four sisters – Nellie, Muriel, Marjorie and Doris. Benjamin married Mary Smith-Dunlop in Stafford in 1917, but they do not appear to have had any children.
Benjamin first served with the 1st Battalion of the South Staffordshire Regiment (number 9047) in France on 17 December 1915 as a Corporal. He was appointed Acting Company Sergeant-Major and later 2nd Lieutenant, and was Mentioned in Despatches, as reported in the London Gazette on 4 January 1917. He appears to have been discharged in 1918 and issued with a Silver War Badge on 4 December 1918, although no further details are available.