James Amphlett described himself on his enlistment document as a transport worker, and on another, later, document as an ironpress worker. He enlisted on 13/1/1915. At the time, he had previous experience in the Citizens' Military Forces and was still serving. He was 20 years old, unmarried, 5' 9" tall, with red hair, brown eyes and a ruddy complexion. Unusually, he allocated part of his wage as a soldier to his brother, William Amphlett, living in the Melbourne suburb of Newmarket. James Amphlett did his training at Broadmeadows with the 6th Battalion, 5th Reinforcements, and was sent to the Dardanelles, where, in July 1915, he was attached to the 58th Battalion. In December, 1915, he was sent to hospital with dysentery, and again on November 28, 1916.

On January 12, 1917,he rejoined his battalion in France, landing at Le Havre and marching out from Etaples. He fought on the Western Front until he was severely wounded in the right leg on March 27, 1918, probably at Corbie, close to Villers-Bretonneux, Somme. On April 22, his right leg was amputated, but he either developed infection in it or it failed to heal, because he was transferred to the 2nd Auxiliary Hospital at Fort Pitt, Chatham, where  his right thigh was amputated. On his recovery, he was invalided out of the army and sent home to Melbourne on the 'Karoola' on December 13, 1918. Telegrams to his father over this period described him as 'dangerously ill' in May; in early June, his condition was 'stationary'; in late June, he was 'convalescent'. A letter from a Miss Eileen Croft, Royal Alfred Hotel, Crown St., Wollongong,  to the army authorities on 4/5/1919, asks that information be sent to her of his condition. She had heard that he was in hospital after having his leg amputated, but that he had been returned to Australia and asked for his address. Sadly, the authorities gave it as 4 Powlett St, instead of 14, so the two may never have been reunited. 

He married Catherine Christine Gardner in 1921. They had two sons, Kenneth, born 1922 and Norman, born 1923. James Henry Amphlett died in 1950, aged 54.