Harold joined the 141st Field Ambulance for duty on 31st May 1918 from Cyclists Base Depot. On 14th July 1918 he was admitted 'sick' to the hospital of his unit, then was discharged from the hospital of the 2nd Field Ambulance and rejoined this unit for duty on 26th July 1918. On 5th July 1919 he was transferred for duty with No 47 Casualty Clearing Station.