 Born in a suburb of Newcastle, New South Wales, Jeffries was employed as a surveyor at a mining company where his father served as general manager following his completion of school. Joining a militia battalion in 1912, he was commissioned as a second lieutenant upon the outbreak of war and tasked with the instruction of volunteers for the newly raised Australian Imperial Force. Transferring into the Australian Imperial Force himself in 1916, Jeffries embarked with his battalion for service on the Western Front. Wounded at Messines, he was promoted to captain before being killed fourteen days short of his twenty-third birthday.
