Henry enlisted into the R.A.M.C. Territorial Force on 28th September 1915 and was embodied into the 1st East Anglian Divisional Field Ambulance, joining the 3/1st East Anglian Field Ambulance for duty. He was 24 years and 9 months old; was a Messenger (Exchange) by trade; and was living at 1.a. Richards Place, Walthamstow, Essex at the time. He was transferred to the Regular Army on 24th March 1917, his service number changing from 2434 to 93341. He embarked at Southampton on 17th May 1917, then disembarking at Havre the next day, entered the war in France on 18th May 1917. He journeyed from Havre to Rouen then joined the Cyclist Base Depot there. He was posted to serve with the 141st Field Ambulance, joining them in the field on 26th May 1917. On 2nd July 1919 he proceeded to No 1 Concentration Camp, Cologne for dispersal and was struck off the strength of the unit. He was disembodied from the Army on 31st March 1920.